From the web app:
* Find a track in the library and add two different mood tags - TAG1 and TAG2.
* Create a smart playlist from TAG1 - go to MUSIC then filter by MOOD and select TAG1.
* Click ADD TO PLAYLIST and label playlist PLAYLIST1.
* Create a smart playlist from TAG2 - go to MUSIC then filter by MOOD and select TAG2.
* Click ADD TO PLAYLIST and label playlist PLAYLIST2.
* You should now have two smart playlists filtering on different moods. Both playlists should contain the same track.
* Sync both playlists to iOS
* Make sure both playlists are synced to the device.
* Notice that only one playlist contains the track.