In a project file theres a file at Unreal Projects/ Saved/ Autosaves/ Game
It has quite a few assets in it that are already in the content folder.
In a test project I deleted the contents of the Autosave/ Game folder and it made no difference to the project at all.
In my main large project though I’m a bit more cautious and thought I’d ask here and try and find out what the Autosave/ Game folders purpose is, and if I delete it’s contents in a mature project I’m not doing something that screws up the whole project 
Thanks.