After receiving 4 Gjallarhorns while I've read how rare it is to receive, I'm not ready to call your theory junk. Sure, it sounds a bit like a conspiracy theory, but it does make sense. You just read so many instances of players getting the same exotics they already have. I've gotten 4 Gjallarhorns and a few Truths, but never have gotten a Suros, Hard Light, Thunderlord, etc... My buddies continuously get the same ones, but no Gjallarhorn. So yeah, it's a crazy theory, but it kind of makes sense.