It happens far less than we think. BYU did it to fill out an independent schedule and to stay relevant, but you're not going to get anyone to agree to a 2-for-1, because they don't have to. Nobody else is in the same position BYU was in.

Big-time programs can get one-offs at home against G5 teams. Any FBS team can get one-offs at home against FCS teams. But BYU isn't going to convince another P4 team to do a 2-for-1. Maybe you could negotiate a third game at a neutral site.