Ensure that the ID3 information is the same for both songs on the View and songs on the computer. This will send back a duplicate error signal to WMP and keep it from doubling up the songs.
Also make sure your firmware is current, as there was a little quirk on the previous firmware that allowed that to happen.

ID3 is tag information. It allows you to edit various things about the song, Artist, Album, year etc. In WMP it can be accessed by rightclicking on the song and selecting Advanced Tag Editor
Firmware revision can be found by going to System Settings, then to Info. It'll be the first string of numbers along the top