Disabling Steam Chat's automatic popup at Windows login startup
Steam keeps making me appear offline in my Friends list
How long does Steam store chat logs? : Steam
How to see full chat history? : Steam
In some cases, the fake admin will ask you to send them the reported duplicate item to check if it was, indeed, a duplicate via the Steam trading function.
Therefore, you should stop running it as administrator.
You need to send the game's appid.