But this may be the correct way.
When I upgraded my local setup Res Manager was installed next to Resource Manager. So now I have Res Manager and Resource manager.
I don't think this is bug. Maybe I did not ran an upgrade in a long time, and since then Resource Manager was changed to Res Manager and the installer did not know how to overwrite the existing module.
I don't think I ever had it as Resource Manager. Maybe install your local copy afresh - it may be something just left over from your development.