What am I doing wrong??

I got a sansa clip 8gb, the manual was practically non existent. When i transfer music from windows media player onto the sansa, why is it copying previously transferred stuff back onto it. I was wondering how i had used all my 8gb so quickly and discovered that it had copied the same albums over again and changed the name to various on the clip. why??

I copied this from an old post but try this:

Plug the player into the computer (If you get an autostart menu just close it), Open WMP then go to the Sync Tab, and click the little arrow below it, then go down on the list to your fuze, a fly out menu will pop up and in that menu you go down to Set Up Sync, and a window called Device Setup will open, At the top left corner, there is a check box that says Sync this device automatically, make sure this is unchecked.If you get a menu when you plug it in, that has to options that wants to know if you want to leave you music on, or delete it and make room for new files, make sure the Leave music on my device option is clicked. You need to be sure Auto Sync is off, and that WMp is not deleting you music so you can add more.