I just had the same problem, and by paying closer attention I figured out I had duplicated files, see image bellow (which occured because I moved them to a different folder from remote but the original files were not deleted by VCS).
If you pay closer attention to the error message, you’ll see it’s pointing out the locations of each of the 2 files. For me, one is in the Framework folder while the other one is directly in Project folder :
Delete the undesired file (make sure you actually move it to bin, not only excluding it from project).
Regenerate .sln if needed (right-click on .uproject file → Generate Visual Studio project files).