You can verify that it belongs to that address... if you right click on the original "3" address in your 2FA wallet, you should be able to view the three public keys that belong to that "3" address. You can then generate the redeem script for this address by following the instructions here:
https://bitcointalksearch.org/topic/m.19830190 (credit to Abdussamad for the Electrum console commands)
Once you have the redeemscript, there are instructions for determining the "1" addresses here:
https://bitcointalksearch.org/topic/m.19853098 (Basically, just do steps 2 and 3, you only need to do the other steps if people want a signed message)
And finally, by using an offline copy of
bitaddress.org (use the Github or zip download links at the bottom of the page and use in a VM or airgapped PC), you can input the two private keys you have generated and see if they match up with the addresses... or alternatively, you can just import those private keys into a new Non-HD Electrum wallet (select the "use public or private keys" option when creating a new "Standard wallet") and see if the "1" addresses match up with those from the redeemscript.
