diff --git a/packages/assets-controllers/CHANGELOG.md b/packages/assets-controllers/CHANGELOG.md
index ccceaea663b..1d02384c41c 100644
--- a/packages/assets-controllers/CHANGELOG.md
+++ b/packages/assets-controllers/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Fix duplicate token in state.allTokens after calling addTokens function with the same token twice ([#6829](https://github.com/MetaMask/core/pull/6829)
+
 ## [80.0.0]
 
 ### Added
diff --git a/packages/assets-controllers/src/TokensController.test.ts b/packages/assets-controllers/src/TokensController.test.ts
index 5bfd1fedd6a..4cc0a1f3f09 100644
--- a/packages/assets-controllers/src/TokensController.test.ts
+++ b/packages/assets-controllers/src/TokensController.test.ts
@@ -1878,6 +1878,71 @@ describe('TokensController', () => {
         },
       );
     });
+
+    it('should not add duplicate tokens to state', async () => {
+      await withController(
+        {
+          mockNetworkClientConfigurationsByNetworkClientId: {
+            networkClientId1: buildCustomNetworkClientConfiguration({
+              chainId: '0x5',
+            }),
+          },
+        },
+        async ({ controller, changeNetwork }) => {
+          changeNetwork({ selectedNetworkClientId: InfuraNetworkType.goerli });
+
+          const tokensToImport = [
+            {
+              address: '0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48', // lowercase USDC
+              symbol: 'USDC',
+              decimals: 6,
+              name: 'USDC',
+              image: 'test',
+              aggregators: [
+                'Metamask',
+                '1inch',
+                'LiFi',
+                'XSwap',
+                'Socket',
+                'Rubic',
+                'Squid',
+                'Rango',
+                'Sonarwatch',
+                'SushiSwap',
+                'PMM',
+                'Bancor',
+              ],
+            },
+          ];
+          // Add tokens for first time in state
+          await controller.addTokens(tokensToImport, 'mainnet');
+          expect(
+            controller.state.allTokens[ChainId.mainnet][
+              defaultMockInternalAccount.address
+            ],
+          ).toStrictEqual([
+            {
+              ...tokensToImport[0],
+              address: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // checksummed USDC
+            },
+          ]);
+
+          // Add same tokens again and check the state does not have duplicate entries
+          await controller.addTokens(tokensToImport, 'mainnet');
+
+          expect(
+            controller.state.allTokens[ChainId.mainnet][
+              defaultMockInternalAccount.address
+            ],
+          ).toStrictEqual([
+            {
+              ...tokensToImport[0],
+              address: '0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48', // checksummed USDC
+            },
+          ]);
+        },
+      );
+    });
   });
 
   describe('watchAsset', () => {
diff --git a/packages/assets-controllers/src/TokensController.ts b/packages/assets-controllers/src/TokensController.ts
index 571e28188de..4c79b375952 100644
--- a/packages/assets-controllers/src/TokensController.ts
+++ b/packages/assets-controllers/src/TokensController.ts
@@ -510,11 +510,18 @@ export class TokensController extends BaseController<
       networkClientId,
     ).configuration.chainId;
 
+    const tokensToImportChecksummed = tokensToImport.map((token) => {
+      return {
+        ...token,
+        address: toChecksumHexAddress(token.address),
+      };
+    });
+
     // Used later to dedupe imported tokens
     const newTokensMap = [
       ...(allTokens[interactingChainId]?.[this.#getSelectedAccount().address] ||
         []),
-      ...tokensToImport,
+      ...tokensToImportChecksummed,
     ].reduce(
       (output, token) => {
         output[token.address] = token;
@@ -523,7 +530,7 @@ export class TokensController extends BaseController<
       {} as { [address: string]: Token },
     );
     try {
-      tokensToImport.forEach((tokenToAdd) => {
+      tokensToImportChecksummed.forEach((tokenToAdd) => {
         const { address, symbol, decimals, image, aggregators, name } =
           tokenToAdd;
         const checksumAddress = toChecksumHexAddress(address);