This is what we call cheesing the Cryptarch. Bungie did not mean for the Cryptarch to a) actually give out not just one, but TWO legendary engrams for all your hard work, and b) for those engrams to turn into something useful and not just energy/shards. This is not how Bungie intended you to get the 2 best weapons in the game. Patch incoming next Tuesday. From here on out, all Cryptarch packages will contain only a "surprise box". This package has a small chance of containing a green engram, but more often than not will spawn a yellow wizard that will chase you around the tower every time you visit. Surprise box contents stack. Don't worry, Bungie has faith that you will never learn how to defeat the wizard(s) without the use of any weapons, but with the rare Crocs of Crota drop, the Wizard won't find you attractive enough to bother you too much while going about your tower activities. (Warning: Crocs of Crota may be glitched and aggro the wizard even more. ETA on fix unknown, will probably drop when Bungie decides to fix the heavy ammo glitch in 2016)