Ok, I suspect this might be a Visual Studio thing, but there must be some reason for this. I created from the list of default items a ListBox (Right Click on project, or fol
Can happen if you are not alert and careful about how you use Resharper.
This happened to me when a I allowed Resharper to auto-import references while I was coding.
So having mistyped initially, then edited the code I was working on, I did not check what it had imported. After running into the same issue, I realised that there was a self-reference in the same library. So there were double implementations of the method in question.