how many of you repurchase your TF toys by mistakes?

i guess most people here have an impressive collection, probably over thousands. some are hidden away, and some are display on shelves. it's safe to say that there's a certain possibility that people will be likely to rebuy the same figure twice or more by mistake. so how do you guys keep track on the figures you already possess and try to avoid repeating the same mistake ever again. ex, do you guys keep track of your existing collection in a computerized database or in some other interesting way? let's say if you want to find a toy in your thousands of collection, how do you search for it?