Anyone who codes know why, and in truth the random number generator is correct for the following reasons: 1. They are pulling the list of exotic weapons and gear, and the generator selects it randomly. 2. RNG in code has repeated issues of selecting the same numbers over and over. If you run the dice roll application, which you learn in a basic programing class, you will see multiple repeats in a 100 rolls. My application had at least 2 repeats. Longest chain of repeats I recalled was 7 or 8. 3. Bungie can easily manipulate data. So after the generator is ran, a developer can write a script to change any weapon or gear upon request. So when IB was requested, it was inserted. The other IB was totally randomized. Issue is they did not store store Xur weekly table, and bounced sold inventory for those weeks. What I would've done was store the data, and checked each item to ensure it wasn't sold the previous cycles. Armor and weapon cycles would be different due to the amount. Of course that change or enhancement would take a while to patch or hot fix out due to Bungies slow testing cycle.