So I sold CS:GO for 2 keys. When I went to collect the keys, i wanted to deposit two more CS:GO's and a spelunky. We both clicked "Make Trade" but the trade bugged and it says items were not exchanged.

After a few mins, I go back to my dispenser to find that 1 key is available for exchange.

Here's a picture of my inventory history:
http://imgur.com/sZMxzmr