[Zeldor]

It's enough if one person cheats and submits old .2h file. I'd ask llambeast to check the situation, find the person behind it and ban him from MP completely, if it's what happened here.

Explanation is simple - someone uses old .2h file and game sees it as valid [game name is fine, turn is fine, nation is fine], but every rollbacks makes some changes in IDs, and it's how things are stored. And there are some weird things that happen if you submit .2h file with IDs different than those you should have. It's usually commanders becoming troops and other way around, magic paths suddenly appearing, you getting commanders in weird places [or scouts becoming commanders and attacking], I have even seen 4 air queens after rollback.