Move content db within same farm but now wrong schema so can't mount!

Question

This is weird.
SharePoint 2010, SP1 (yes, I know, rather out of date).
I moved a content db to a different drive on our SQL server.  Removed it in SP, detached in SQL Server, moved the mdf and ldf file, and re-attached in SQL server.  But when I try to add it back to SharePoint, I'm told that the schemas don't match.
I did *nothing else* at the time.  This is all within the same farm, and all the members are at the same patch level.
Does anyone have any ideas?  Please?
Rob Schifreen SharePoint 2010 Admin University of Brighton, UK

Answer 1

Thanks to both respondents for your suggestions.  As it turns out, the error was my fault, though I wish it hadn't taken me a whole day to figure out.
I have a script which runs a couple of times a day, to create a MySite for any new user who doesn't currently have one.  I unmounted a load of mysite content databases in order to move them to the new drive.  Shortly after which, the script ran,
and thus created empty sites in the place of the ones I'd temporarily removed!
Thankfully my script keeps a log of everything it does, so it was then relatively easy to delete the new empty sites.  Once I did this, and then did the server upgrades I was also intending to do at the same time, I could re-mount the old MySites just
fine.
For future reference, the best clue was the warning about duplicated sites that I got from doing a test-spcontentdatabase in PowerShell.  Definitely something I intend to run regularly now, to check for problems.
Rob Schifreen SharePoint 2010 Admin University of Brighton, UK