Does importing a playlist import the songs again?

Hi there,

I create my playlists using Zune software because I prefer it, and to get the playlists onto my iPhone and iPad, I import them using the import feature. Whenever I add new songs to the playlist, I delete from iTunes and re-import.

My problem is with duplicates. I have lost track of how many times I have deleted duplicate songs in my library, when I know for a fact there are not physical duplicates in my music folder, but they just keep reappearing. Are the duplicates occurring when I import the playlists? I thought playlist would just be a list of the songs in the playlist, and should not appear as duplicates.

FYI I have 'copy files to iTunes media folder' turned off. My media is stored on a separate media PC, which isn't where iTunes is installed.

Thanks if anyone is able to help.