diff --git a/packages/react-dom/src/__tests__/ReactDOMAttribute-test.js b/packages/react-dom/src/__tests__/ReactDOMAttribute-test.js
index b8feea0e675..33ebaa179b6 100644
--- a/packages/react-dom/src/__tests__/ReactDOMAttribute-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMAttribute-test.js
@@ -106,7 +106,7 @@ describe('ReactDOM unknown attribute', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'Warning: The provided `unknown` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
diff --git a/packages/react-dom/src/__tests__/ReactDOMComponent-test.js b/packages/react-dom/src/__tests__/ReactDOMComponent-test.js
index 2e903aba8ab..3ee19c72e2e 100644
--- a/packages/react-dom/src/__tests__/ReactDOMComponent-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMComponent-test.js
@@ -276,7 +276,7 @@ describe('ReactDOMComponent', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'Warning: The provided `fontSize` CSS property is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
diff --git a/packages/react-dom/src/__tests__/ReactDOMInput-test.js b/packages/react-dom/src/__tests__/ReactDOMInput-test.js
index 474cae8bb60..cdad638c6ad 100644
--- a/packages/react-dom/src/__tests__/ReactDOMInput-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMInput-test.js
@@ -631,7 +631,7 @@ describe('ReactDOMInput', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'Form field values (value, checked, defaultValue, or defaultChecked props) must be ' +
-        'strings, not TemporalLike. This value must be coerced to a string before before using it here.',
+        'strings, not TemporalLike. This value must be coerced to a string before using it here.',
     );
   });
 
@@ -655,7 +655,7 @@ describe('ReactDOMInput', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'Form field values (value, checked, defaultValue, or defaultChecked props) must be ' +
-        'strings, not TemporalLike. This value must be coerced to a string before before using it here.',
+        'strings, not TemporalLike. This value must be coerced to a string before using it here.',
     );
   });
 
@@ -679,7 +679,7 @@ describe('ReactDOMInput', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'Form field values (value, checked, defaultValue, or defaultChecked props) must be ' +
-        'strings, not TemporalLike. This value must be coerced to a string before before using it here.',
+        'strings, not TemporalLike. This value must be coerced to a string before using it here.',
     );
   });
 
@@ -703,7 +703,7 @@ describe('ReactDOMInput', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'Form field values (value, checked, defaultValue, or defaultChecked props) must be ' +
-        'strings, not TemporalLike. This value must be coerced to a string before before using it here.',
+        'strings, not TemporalLike. This value must be coerced to a string before using it here.',
     );
   });
 
diff --git a/packages/react-dom/src/__tests__/ReactDOMSelect-test.js b/packages/react-dom/src/__tests__/ReactDOMSelect-test.js
index 9037028b9f0..4332c52d124 100644
--- a/packages/react-dom/src/__tests__/ReactDOMSelect-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMSelect-test.js
@@ -1054,7 +1054,7 @@ describe('ReactDOMSelect', () => {
       ).toErrorDev(
         'Form field values (value, checked, defaultValue, or defaultChecked props)' +
           ' must be strings, not TemporalLike. ' +
-          'This value must be coerced to a string before before using it here.',
+          'This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1074,7 +1074,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1094,7 +1094,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1120,7 +1120,7 @@ describe('ReactDOMSelect', () => {
       ).toErrorDev(
         'Form field values (value, checked, defaultValue, or defaultChecked props)' +
           ' must be strings, not TemporalLike. ' +
-          'This value must be coerced to a string before before using it here.',
+          'This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1147,7 +1147,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1174,7 +1174,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1193,7 +1193,7 @@ describe('ReactDOMSelect', () => {
       ).toErrorDev(
         'Form field values (value, checked, defaultValue, or defaultChecked props)' +
           ' must be strings, not TemporalLike. ' +
-          'This value must be coerced to a string before before using it here.',
+          'This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1213,7 +1213,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1233,7 +1233,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1259,7 +1259,7 @@ describe('ReactDOMSelect', () => {
       ).toErrorDev(
         'Form field values (value, checked, defaultValue, or defaultChecked props)' +
           ' must be strings, not TemporalLike. ' +
-          'This value must be coerced to a string before before using it here.',
+          'This value must be coerced to a string before using it here.',
       );
     });
 
@@ -1286,7 +1286,7 @@ describe('ReactDOMSelect', () => {
         expect(test).toThrowError(new TypeError('prod message')),
       ).toErrorDev(
         'The provided `value` attribute is an unsupported type TemporalLike.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
       );
     });
   });
diff --git a/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js b/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
index 34794223406..d4cb435688d 100644
--- a/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
+++ b/packages/react-dom/src/__tests__/ReactDOMTextarea-test.js
@@ -251,7 +251,7 @@ describe('ReactDOMTextarea', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'Form field values (value, checked, defaultValue, or defaultChecked props) must be ' +
-        'strings, not TemporalLike. This value must be coerced to a string before before using it here.',
+        'strings, not TemporalLike. This value must be coerced to a string before using it here.',
     );
   });
 
diff --git a/packages/react-dom/src/__tests__/ReactIdentity-test.js b/packages/react-dom/src/__tests__/ReactIdentity-test.js
index 9dcfe5a1842..47814fc39d1 100644
--- a/packages/react-dom/src/__tests__/ReactIdentity-test.js
+++ b/packages/react-dom/src/__tests__/ReactIdentity-test.js
@@ -288,7 +288,7 @@ describe('ReactIdentity', () => {
       expect(test).toThrowError(new TypeError('prod message')),
     ).toErrorDev(
       'The provided key is an unsupported type TemporalLike.' +
-        ' This value must be coerced to a string before before using it here.',
+        ' This value must be coerced to a string before using it here.',
       {withoutStack: true},
     );
   });
diff --git a/packages/shared/CheckStringCoercion.js b/packages/shared/CheckStringCoercion.js
index a229ac6dae9..52e05205981 100644
--- a/packages/shared/CheckStringCoercion.js
+++ b/packages/shared/CheckStringCoercion.js
@@ -78,7 +78,7 @@ export function checkAttributeStringCoercion(
     if (willCoercionThrow(value)) {
       console.error(
         'The provided `%s` attribute is an unsupported type %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         attributeName,
         typeName(value),
       );
@@ -92,7 +92,7 @@ export function checkKeyStringCoercion(value: mixed): void | string {
     if (willCoercionThrow(value)) {
       console.error(
         'The provided key is an unsupported type %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         typeName(value),
       );
       return testStringCoercion(value); // throw (to help callers find troubleshooting comments)
@@ -108,7 +108,7 @@ export function checkPropStringCoercion(
     if (willCoercionThrow(value)) {
       console.error(
         'The provided `%s` prop is an unsupported type %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         propName,
         typeName(value),
       );
@@ -125,7 +125,7 @@ export function checkCSSPropertyStringCoercion(
     if (willCoercionThrow(value)) {
       console.error(
         'The provided `%s` CSS property is an unsupported type %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         propName,
         typeName(value),
       );
@@ -139,7 +139,7 @@ export function checkHtmlStringCoercion(value: mixed): void | string {
     if (willCoercionThrow(value)) {
       console.error(
         'The provided HTML markup uses a value of unsupported type %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         typeName(value),
       );
       return testStringCoercion(value); // throw (to help callers find troubleshooting comments)
@@ -153,7 +153,7 @@ export function checkFormFieldValueStringCoercion(value: mixed): void | string {
       console.error(
         'Form field values (value, checked, defaultValue, or defaultChecked props)' +
           ' must be strings, not %s.' +
-          ' This value must be coerced to a string before before using it here.',
+          ' This value must be coerced to a string before using it here.',
         typeName(value),
       );
       return testStringCoercion(value); // throw (to help callers find troubleshooting comments)