Update bridges.md

specs/bridges.md

@@ -22,7 +22,6 @@ The `L2StandardBridge` is a predeploy contract located at
 
 ```solidity
 interface StandardBridge {
-    event ERC20BridgeFinalized(address indexed localToken, address indexed remoteToken, address indexed from, address to, uint256 amount, bytes extraData);
     event ERC20BridgeFinalized(address indexed localToken, address indexed remoteToken, address indexed from, address to, uint256 amount, bytes extraData);
     event ERC20BridgeInitiated(address indexed localToken, address indexed remoteToken, address indexed from, address to, uint256 amount, bytes extraData);
     event ETHBridgeFinalized(address indexed from, address indexed to, uint256 amount, bytes extraData);