How are you supposed to remember which folio's you have bought?

HedgeHugger

I recently bought the Skyrim folio from Rolis's assistant. I had no idea I had already bought it. I know I could sell the blueprints, but opted to give them to my Oh instead. Annoying that there was no indicator to show that I owned everything already.
Not to be too down about it, I bought the Morrowind one, only to find that once again I'd bought it before!! Daft, on me, eh! OH had another load of blueprints.

Now I am totally put off trying to get anymore (I know I don't have them all), but cannot afford to keep throwing away hours worth of Master writting time. No idea which ones I have, no way to keep track easily (XBOX), no doubt PC has some add on or another.
Give us a clue that the folio has been previously purchased, please.