I believe I saw this mentioned in this very sub a few months ago but I cannot recall specifics for the life of me. I remember someone discussing reverse engineering and using a captured American bomber as an example.
The bomber had been repaired quickly due to a stray bullet and had a large steel plate welded to the wing. The Russian engineers thought it was some sort of design choice and their knockoff copies of the plane all featured a plate in that location on the wing.
Is this a thing that happened or am I going insane?
The aircraft you're referring to is the Tupolev Tu-4 "Bull", which was a copy of the B-29 Superfortress. However, the story of the patch is slightly different - it wasn't because Soviet engineers thought it was a deliberate design choice, but rather the replication of the patch was a political decision. Tupolev had been told to produce an exact replica of the B-29, but wanted to make minor changes to the design to suit Soviet industry and technology. To mollify the politicians, the engineers made the aircraft cosmetically as close as possible to the American examples they had. This included matching paint samples, and buying surplus B-29 tires from the US, as well as copying the patch. They were well aware that the patch was unnecessary for the aircraft to fly.
For more information on the story of the Tu-4, see this article - the story of the patch is on page 5 and 6.