My choice of the 2600 cart was a very poor example.
What I should of said was that unless it is a dump of the actual arcade pcb, it is not the same version and is covered under a different copyright. Ownership of a psx cd does not constitute legal rights to the arcade roms of the same name. Being Sony, I'm sure that there is some kind of Sony/Namco joint copyright or something on the psx disc. Another way to tell that they aren't the same version is because the true arcade Pac-Man rom will not run on the psx without some kind of modification of either the psx or the rom itself.
You may try it, but be wary of your successful bidder. If I purchased a "legal" version of an arcade rom and found out I bought a psx disc, I'd be a little ticked and most likely leave negative feedback. But that's just me.