I don’t think so, maybe someone else will chime in. Otherwise I goofed around a little bit in mame debugger and I don't think there's a quick way to patch it up. As it is, the coin chutes are connected to each turtle.
$1c0100 is the coin memory location. The word shows what's happening:
00FF - nothing
00FE - 1p coin
00FD - 2p coin
00FB - 3p coin
00F7 - 4p coin
Start buttons are at:
$1c0000 - p1
$1c0002 - p2
$1c0004 - p3
$1c0006 - p4
word 00FF = nothing, 00EF 'start'
I can't think of a clean way to pool coins because of the way it currently tracks credits. When you add a coin, it gives you 2 lives regardless of if you're playing or what. I thought about adding credits to all turtles, then subtracting 2 from the other turtles when you press Start, but that leads to weird situations during gameplay where you can add a coin and not have to hit start, so everyone gets +2.
I think the right hack would be to build a credit pool and gut out the existing stuff, but that's probably more work than I want to do right now. Maybe if
@kuze is feeling frisky.
But I do have the 2p board and I have it on freeplay right now (which I don't particularly like). So this might sit in my head a little more and if I come up with a good idea I may crack open the debugger again. I already have an editing environment set up for it, so it's just waiting on the right idea. (also with this many edits the checksum would have to be handled directly vs. the way the existing patch does it... but I think I can get that solved).