> File X is originally BSD+MAME but someone makes a contribution agreeing only to the > MAME license. In or out of MAME I don't see how that file can be licensed BSD with > those changes.
In that case the patched file would only bear the MAME license. Legally that's fine; in reality my previous mention of not being a dick would (hopefully) come into play since you are restricting the code beyond the intent of the original author(s).