Please ignore the other guy. Your addresses can't possibly be the same because according to the OP your electrum wallet is a multisig wallet between electrum generated seed and coinbase's extended public key. Coinbase knows nothing of your electrum wallet so the addresses can't possibly be the same.
What you need to do is create a new wallet like this:
file new/restore > enter name for your new wallet, click next,
select multisig wallet, next
from 2 require 2, next
select "i already have a seed", next
enter your seed from your electrum wallet, next, next,
select " enter cosigner key", next
now past the xprv for the user key from coinbase. the xprv is the master private key or extended private key not the extended public key. it has to be the xprv of the User key in your coinbase wallet because it that key's public component that you used. if there is no option to get the extended private key then you are in trouble
after that you just click next next until you are done creating the wallet.
So once again you need the extended private key (xprv) of the User from your coinbase wallet. If you can't figure out how to get that then you can't be helped.