Why does wifi sync resync everything twice?

[beaches]

When I hook up with the USB and send a playlist by right clicking and send to device it sends many GB very fast. Then when I do a synch through the app on the phone it wants to delete all those files so I say no, then it redownloads all of them. To the same folder and location. Why?

[Lowlander]

Which version of MMA and MMW?