I've posted on the Pioneer DJ forums as well but I thought I would post here because I think the problem is caused by the Traktor import procedure, it uses the 'newest' name for a track that may have been changed in Traktor, so is different from the original file name. This appears to cause problems in Rekordbox.
I could be wrong though, but this is how it looks. I was hoping someone else might have had the same problem.
Thanks for the reply though
