Same room. Most of this is planning ahead for a what if scenario. But just in case it comes to fruition, I want to be prepared.
It's also based on timing. If were to get my hands on a second set of M80s while I'm in my current location, I had thought about putting the second set on top of the first set, but inverted. (tweeter to tweeter) This would basically create a pair of M160s (sort of).
The more likely scenario would be for a much larger room with them set up in normal fashion with approximately 10' between them. M80(L2) - 10' - M80(L1) - 10' - M80(R1) - 10' - M80(R2)