You can import your second MetaMask-created account by choosing the "other" custom import option with your 12-word phrase. Then on the custom derivation path screen enter m/44'/60'/0'/0/1 check that the address underneath matches the correct account. Change the last digit to 0,1,2,3,...,etc. if you have multiple accounts in your MetaMask.
Note that this is only for MetaMask-created accounts, this does not include LOOSE accounts imported into MetaMask.