MAME games 2 player start



I’m in the early stages of planning a build using a Picade HAT. I already had a Pi, so I’ve installed RetroPie on it and I’ve been playing some games using my TV and a keyboard. With MAME games I can insert two or more coins and then press 2 on the keyboard to start a two player game, where players take alternate turns. Is it possible to do this with the Picade HAT? I’ve read up on it, and searched these forums, but I can’t find any mention of key 2 being supported.

Thanks in advance for any help anyone can give me.