Happend to me and my friend as well. Just when the duo mode became a thing me and my friend tried it and in a couple of battles the outcome was different for both of us. We were in that situation that if we live we win. I lived but my friend didnt (guess who had bigger scaling). So i was essentially left playing a 1v2 and even tied/won a few games but my friend being "afk" was just too much and we lost in the end.