Well, not exactly. A couple of things: if you got PSE bundled with a scanner or something, then yeah, you probably got both platform versions. Otherwise, standalone versions of PSE 8 were single-platform--mac serial numbers don't work in windows and windows serial numbers don't work for macs.
Also, there is no organizer in PSE 8/mac. It came with bridge instead. Bridge can read metadata keywords, but not organizer catalogs, and PSE 8 mac would not understand an organizer backup. Even with later versions after adobe started including organizer for macs, you would need at least PSE 9 in windows for the mac version to understand it.
