I've been talking about this since I started Destiny. It should be a great new system of RNG in TTK, that analyzes what gear you've got, and tries to avoid duplicates. This ultimately pushes up the chances for getting the gear you're actually wanting. It always seemed like a simple "if this then that" logic could be applied to the RNG coding.
"If (have) Dragons Breath, (then) RNG rate drops dramatically"
Glad to see they are really considering the back end with the new expansion.