Sometimes duplicate uniques are generated

[tehtmi]

It is possible for the same unique item to be picked up more than once in the same game.

This problem seems to be caused when the game reuses cached item lists with uniques in them that have since been found.

(I've had this happen personally with GCBs. -- tehtmi)

[tehtmi]

Item lists are still cached, but with all unique items included. Whatever function uses the list must check for duplicates.