diff --git a/packages/gatsby/src/internal-plugins/query-runner/redirects-writer.js b/packages/gatsby/src/internal-plugins/query-runner/redirects-writer.js
index 8a12f9923d7e5..b31e3c7b8560c 100644
--- a/packages/gatsby/src/internal-plugins/query-runner/redirects-writer.js
+++ b/packages/gatsby/src/internal-plugins/query-runner/redirects-writer.js
@@ -1,8 +1,11 @@
 import _ from "lodash"
+import crypto from "crypto"
 import fs from "fs-extra"
 import { store, emitter } from "../../redux/"
 import { joinPath } from "../../utils/path"
 
+let lastHash = null
+
 const writeRedirects = async () => {
   bootstrapFinished = true
 
@@ -11,6 +14,17 @@ const writeRedirects = async () => {
   // Filter for redirects that are meant for the browser.
   const browserRedirects = redirects.filter(r => r.redirectInBrowser)
 
+  const newHash = crypto
+    .createHash(`md5`)
+    .update(JSON.stringify(browserRedirects))
+    .digest(`hex`)
+
+  if (newHash === lastHash) {
+    return Promise.resolve()
+  }
+
+  lastHash = newHash
+
   await fs.writeFile(
     joinPath(program.directory, `.cache/redirects.json`),
     JSON.stringify(browserRedirects, null, 2)
diff --git a/packages/gatsby/src/redux/reducers/redirects.js b/packages/gatsby/src/redux/reducers/redirects.js
index aa6cca9ecdf3f..9cdd8eabcdb1e 100644
--- a/packages/gatsby/src/redux/reducers/redirects.js
+++ b/packages/gatsby/src/redux/reducers/redirects.js
@@ -1,7 +1,15 @@
+const _ = require(`lodash`)
+
 module.exports = (state = [], action) => {
   switch (action.type) {
-    case `CREATE_REDIRECT`:
-      return [...state, action.payload]
+    case `CREATE_REDIRECT`: {
+      if (!state.some(redirect => _.isEqual(redirect, action.payload))) {
+        // Add redirect only if it wasn't yet added to prevent duplicates
+        return [...state, action.payload]
+      }
+      return state
+    }
+
     default:
       return state
   }