I had something similar happen long ago, before Burning Crusade and before I started multiboxing. We were doing 15 man premades for AB and we notice we had a pug in the group. So we ask in vent who didn't get in the queue. And it turned out that we all made it. It was 16 on 14. And it was like that for 3 games in a row and then stopped. We weren't sure how it happened though.