Well if they're duplicated in the file browser too, then one of two things explain it :
1) You have multiple copies of the same file on your DAP, in which case of course the database contains duplicates
2) The filesystem on your DAP is damaged in a unique and interesting way, and this will too cause issues with the database.
So I suggest your run a chkdsk / fsck against your sansa and see if that fixes it.