I was afraid of that.
I googled the problem but couldn't find anything at the time, though it seems to me more people should have experienced this since arcade games are popular among retro gamers and users of LB and BB.
You can't have one person adding coins while the other presses start or you'll exit the game.
At least with the default bindings of select and start.
So I'm guessing BB users bind the coin button to something else or do they use another more sophisticated solution?