diff --git a/common/store.ts b/common/store.ts
index bbc1a92b..6bc9a7e9 100644
--- a/common/store.ts
+++ b/common/store.ts
@@ -19,6 +19,7 @@ import RootReducer from './reducers';
 import promiseMiddleware from 'redux-promise-middleware';
 import { getNodeConfigFromId } from 'utils/node';
 import { getNetworkConfigFromId } from 'utils/network';
+import { dedupeCustomTokens } from 'utils/tokens';
 import sagas from './sagas';
 import { gasPricetoBase } from 'libs/units';
 
@@ -59,7 +60,6 @@ const configureStore = () => {
         }
       : { ...swapInitialState };
 
-  const localCustomTokens = loadStatePropertyOrEmptyObject<CustomTokenState>('customTokens');
   const savedTransactionState = loadStatePropertyOrEmptyObject<TransactionState>('transaction');
   const savedConfigState = loadStatePropertyOrEmptyObject<ConfigState>('config');
 
@@ -82,6 +82,13 @@ const configureStore = () => {
     }
   }
 
+  // Dedupe custom tokens initially
+  const savedCustomTokensState =
+    loadStatePropertyOrEmptyObject<CustomTokenState>('customTokens') || customTokensInitialState;
+  const initialNetwork =
+    (savedConfigState && savedConfigState.network) || configInitialState.network;
+  const customTokens = dedupeCustomTokens(initialNetwork.tokens, savedCustomTokensState);
+
   const persistedInitialState = {
     config: {
       ...configInitialState,
@@ -100,7 +107,7 @@ const configureStore = () => {
             : transactionInitialState.fields.gasPrice
       }
     },
-    customTokens: localCustomTokens || customTokensInitialState,
+    customTokens,
     // ONLY LOAD SWAP STATE FROM LOCAL STORAGE IF STEP WAS 3
     swap: swapState
   };
diff --git a/common/utils/tokens.ts b/common/utils/tokens.ts
new file mode 100644
index 00000000..23d44baf
--- /dev/null
+++ b/common/utils/tokens.ts
@@ -0,0 +1,18 @@
+import { Token } from 'config/data';
+
+export function dedupeCustomTokens(networkTokens: Token[], customTokens: Token[]): Token[] {
+  if (!customTokens.length) {
+    return [];
+  }
+
+  // If any tokens have the same symbol or contract address, remove them
+  const tokenCollisionMap = networkTokens.reduce((prev, token) => {
+    prev[token.symbol] = true;
+    prev[token.address] = true;
+    return prev;
+  }, {});
+
+  return customTokens.filter(token => {
+    return !tokenCollisionMap[token.address] && !tokenCollisionMap[token.symbol];
+  });
+}
diff --git a/spec/utils/tokens.spec.ts b/spec/utils/tokens.spec.ts
new file mode 100644
index 00000000..dcf96822
--- /dev/null
+++ b/spec/utils/tokens.spec.ts
@@ -0,0 +1,47 @@
+import { dedupeCustomTokens } from 'utils/tokens';
+
+describe('dedupeCustomTokens', () => {
+  const networkTokens = [
+    {
+      address: '0x48c80F1f4D53D5951e5D5438B54Cba84f29F32a5',
+      symbol: 'REP',
+      decimal: 18
+    },
+    {
+      address: '0xa74476443119A942dE498590Fe1f2454d7D4aC0d',
+      symbol: 'GNT',
+      decimal: 18
+    }
+  ];
+
+  const DUPLICATE_ADDRESS = {
+    address: networkTokens[0].address,
+    symbol: 'REP2',
+    decimal: 18
+  };
+  const DUPLICATE_SYMBOL = {
+    address: '0x0',
+    symbol: networkTokens[1].symbol,
+    decimal: 18
+  };
+  const NONDUPLICATE_CUSTOM = {
+    address: '0x7cB57B5A97eAbe94205C07890BE4c1aD31E486A8',
+    symbol: 'MEW',
+    decimal: 0
+  };
+
+  const customTokens = [DUPLICATE_ADDRESS, DUPLICATE_SYMBOL, NONDUPLICATE_CUSTOM];
+  const dedupedTokens = dedupeCustomTokens(networkTokens, customTokens);
+
+  it('Should remove duplicate address custom tokens', () => {
+    expect(dedupedTokens.includes(DUPLICATE_ADDRESS)).toBeFalsy();
+  });
+
+  it('Should remove duplicate symbol custom tokens', () => {
+    expect(dedupedTokens.includes(DUPLICATE_SYMBOL)).toBeFalsy();
+  });
+
+  it('Should not remove custom tokens that aren’t duplicates', () => {
+    expect(dedupedTokens.includes(NONDUPLICATE_CUSTOM)).toBeTruthy();
+  });
+});