The Collector trait helps sims find two collectibles in one spot (Solved).

This clears up A LOT of mystery for me. I do have a sim working on the Archaeology Achievement and digs up two of everything. It does say in the description of the Geek Trait that they do better at collecting. "These Sims become Happy when Reading Sci-Fi or Playing Video Games, may become Tense if they haven't played much, are better at finding Collectibles, and can Discuss Geek Things with other Geek Sims." Mystery solved. I thought it was mod.