Traditionally, Bradley has always played one exhibition on-campus and another at PCC. The year the Fieldhouse went down to construct RC, also happened to be the year the NCAA began allowing closed-door scrimmages, so for a few years BU did that (IIRC against DePaul and Illinois) and then just played one exhibition at PCC.
Moving forward, I think 2 regular season games will become the norm, in an effort to increase the overall number of home games every year.