diff --git a/x/staking/types/authz.go b/x/staking/types/authz.go
index cacf5e225dbb..d3c7425d6ade 100644
--- a/x/staking/types/authz.go
+++ b/x/staking/types/authz.go
@@ -164,14 +164,24 @@ func validateAllowAndDenyValidators(allowed, denied []sdk.ValAddress) ([]string,
 
 	allowedValidators := make([]string, len(allowed))
 	if len(allowed) > 0 {
+		foundAllowedValidators := make(map[string]bool, len(allowed))
 		for i, validator := range allowed {
+			if foundAllowedValidators[validator.String()] {
+				return nil, nil, sdkerrors.ErrInvalidRequest.Wrapf("duplicate allowed validator address: %s", validator.String())
+			}
+			foundAllowedValidators[validator.String()] = true
 			allowedValidators[i] = validator.String()
 		}
 		return allowedValidators, nil, nil
 	}
 
 	deniedValidators := make([]string, len(denied))
+	foundDeniedValidators := make(map[string]bool, len(denied))
 	for i, validator := range denied {
+		if foundDeniedValidators[validator.String()] {
+			return nil, nil, sdkerrors.ErrInvalidRequest.Wrapf("duplicate denied validator address: %s", validator.String())
+		}
+		foundDeniedValidators[validator.String()] = true
 		deniedValidators[i] = validator.String()
 	}
 
diff --git a/x/staking/types/authz_test.go b/x/staking/types/authz_test.go
index 8ef9a9b3868e..fa6185293ec5 100644
--- a/x/staking/types/authz_test.go
+++ b/x/staking/types/authz_test.go
@@ -42,6 +42,14 @@ func TestAuthzAuthorizations(t *testing.T) {
 	_, err = stakingtypes.NewStakeAuthorization([]sdk.ValAddress{val1, val2}, []sdk.ValAddress{val1}, stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_DELEGATE, &coin100)
 	require.Error(t, err)
 
+	// error duplicate allow list
+	_, err = stakingtypes.NewStakeAuthorization([]sdk.ValAddress{val1, val1}, []sdk.ValAddress{}, stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_DELEGATE, &coin100)
+	require.ErrorContains(t, err, "duplicate allowed validator address")
+
+	// error duplicate denied list
+	_, err = stakingtypes.NewStakeAuthorization([]sdk.ValAddress{}, []sdk.ValAddress{val1, val1}, stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_DELEGATE, &coin100)
+	require.ErrorContains(t, err, "duplicate denied validator address")
+
 	// verify MethodName
 	undelAuth, _ := stakingtypes.NewStakeAuthorization([]sdk.ValAddress{val1, val2}, []sdk.ValAddress{}, stakingtypes.AuthorizationType_AUTHORIZATION_TYPE_UNDELEGATE, &coin100)
 	require.Equal(t, undelAuth.MsgTypeURL(), sdk.MsgTypeURL(&stakingtypes.MsgUndelegate{}))