Hi, thanks a lot to everybody for the answers! And my apologize to not being clear in my question.
I have a panel with just one coin button. And more or less, a part games like vendetta, it works, even with other emulators. But of course I'd like to have a complete experience, so I'm trying to figure out a way without changing panel, if there is no solution I'll dig another hole, but is going to be a quite a mess, so I'd like to avoid it.
I try to wire player2 coin to player1 coin. It works, everytime I press coin button I get 2 coins and with vendetta games I have another player ready to go. But with other emulators it's a mess, it's like pressing select button at the same time for both users and as example for PC Engine games I had lot's of problem, so I roll back.
The only working way, without doing another hole, in my opinion, it's a combo buttons (hot-key), like Start Player 2 + A player 2 button = player 2 coin, something like that. I'm using XiMo interface, and reading around I did not find any useful instruction on how to do it. Hot-keys are only available for particular purpose as far as I understand.
thanks again