We have seen this issue for sometime on the mac but now it also seems to be affecting windows with the release of 4.6.
If I duplicate an asset that is under version control (perforce) and hence has its read only flag set the duplicate will appear in the editor as though it is not checked out. We can work around this by finding the file, setting it to writeable and then marking it for add but a proper fix would be great.
Many thanks!
Neil