Albums have suddenly started to behave strangely.

Hello all, I hope someone can help me.

I noticed the other day that a few albums in my library had suddenly split into multiple albums. At first I thought there may have been an update that had changed the way certain albums were tagged. I did some rudimentary checks on the album tags (I use Tag & Rename) but couldn't see any issues. However on further examination I noticed that the multiple of the albums had the same track in them see images below.

You can see that a look into the folder for this album shows 11 tracks. 

Doing a re-scan of the library does not fix the issue. But I have found that by adding a new album to my library fixes the issue after a re-scan. However I have noticed that adding a new album can correct one problem but then suddenly another suddenly is inflicted with the same issue.

So I am very confused as why adding one album can suddenly cause this issue with other completely unrelated albums. Sorry to have rambled on.

Any thoughts anyone? 

Anthony