dupe exploit

 Redirected Here from Steam Support: Possible New Dupe Glitch Discovered
Ticket Sent into Steam Support, They Redirected me here to the TF2 forums so that it would be Seen by a TF2 Community Moderator

Possible New TF2 Dupe Glitch Discovered
Trade Partner: Fishy

We were in a Public TF2 Community Server doing a Trade in the SHIFT+TAB Menu
After Reaching an Conclusion on what we would trade for what, Fishy found that he couldn't put items in his side of the trade window. so he tried to add me and said that he couldn't add me.
I added him. He Sent the trade, but the Confirm didn't show up for him on his Steam Mobile app for a minute. I made a trade offer and he got the confirm through. I checked the offer forgetting about my trade offer confirm and after accepting the trade there was 2 confirms. I didn't know which one to accept, so I accepted the oldest / the 2nd one first. Didn't seem to do anything after a second. I accepted the top one and then it went through
He tells me through steam chat that he got my Item and a Refined Metal. We check our Inventory Histories and see this:
- Screenshot (500) My Inventory History
- Screenshot (504) His Inventory History
I go to check my incoming Trade history to find that it didn't go through, It was canceled, despite my Confirm seeming to go through, and my Sent Trade Went through
- Screenshot (501) Incoming Trade Offers
- Screenshot (505) Sent Trade Offers
I believe these are all the steps seen to recreate the bug
My guess was that Steam Canceled the offer as I accepted it, but now that I see that My Trade went through, I don't know how he got his ref from the canceled trade. though I have all my Thirty ref and 2 keys and he got my Kit, but also got 1 Ref out of thin air.
- Screenshot (507) - Their Trade History, Their Last Trade was Roughly 1 Year ago.

I wanted to clarify, The Trade I did went through normally, That doesn't need to be revered unless necessary. The problem here is that a new item was created during his Trade Failing and then somehow duping something
My Guess is that it was the first item that they put up in the Trade window, which was 1 ref. which is currently being valued by the Community at $0.024 According to backpack.tf so not a very big deal, but still something that shouldn't exist. but some traders tend to put most Expensive first on the trade, like I did with my Mann Co. Supply Crate Keys. So if it does actually dupe the first item and not a random item from the trade, it is possible it would dupe items of higher value like Unusuals, Stranges, Keys, etc.

[10:53 AM] Partydonut214:
I think I know why there were 2 confirms
One was mine and one was yours
I accepted mine and then yours
but you also accepted mine

[10:54 AM] Fishy:
Yeah i accepted 2 as well

[10:54 AM] Partydonut214:
but it canceled yours
so yours failed
but it seems to have Duplicated your first item
and my trade went smoothly
- Screenshot (508) - Screenshot of the Chat
- Quick Chat update, as I realized during writing out this ticket that the second confirm was my trade offer pending confirm and not his twice. he notes that he had to confirm 2 as well.

Another New Quick note I forgot to add was I had received a Weapon Drop before the In-game trade that wasn't accepted until after the final trade. Doubt that makes any difference but is helpful to note in case it somehow impacted something.

Posting this now, I will edit to include the Screenshots in a moment.

screenshots:
https://steamcommunity.com/sharedfiles/filedetails/?id=2912992991
https://steamcommunity.com/sharedfiles/filedetails/?id=2912992413
https://steamcommunity.com/sharedfiles/filedetails/?id=2912993529
https://steamcommunity.com/sharedfiles/filedetails/?id=2912993924
https://steamcommunity.com/sharedfiles/filedetails/?id=2912994500
https://steamcommunity.com/sharedfiles/filedetails/?id=2912998761