Double entry albums - know whats causing it but how do I fix it?

Browsing my music by albums and I noticed a lot of albums were in twice?
Went into Additional Info to check file location (wondering if I had more than one copy on hard drive) but nope, one copy but two entries in the LMS database.

File location the same for both entries, but one is the physical location (M:\Music\Artist\Album) the other is the network location of that same album? (Http:/Server....etc)

Interestingly its not the case for every album.
Is there a software switch somewhere to stop this happening?

Thanks.