GamersGate Allows Duplicate Purchases

I'm frustrated with GamersGate. It doesn't notify you if you already own a game and it doesn't stop you from making a duplicate purchase. Steam and GOG show you in a game's page on each store if you already own the game. This prevents you from making a duplicate purchase.

I bought a game pack of four adventure games on sale at GamerGate which included Black Mirror 2. I was hurriedly deciding which game to buy, thinking either the sale was ending soon or there was a pricing error that could end at any moment, so I got confused and mistakenly bought Black Mirror 2 again at GamersGate without thinking twice.  It only cost me $0.59 but I'm frustrated that I still wasted money.