Duplicate Tracks in "Music" App
You should have duplicate tracks on iTunes as well. If not, then try this out


Plug in you iPad and open iTunes. 
On the "File" Menu Click on "Transfer Purchases from Brent's iPad" (I
Assumed the name of your iPad but you get the point).
Wait for sometime for all of your purchased tracks to transfer into
you computer (PC right?).
After that you can try out the steps mentioned in the link you
posted. This will erase all the duplicates from your iTunes Library.
After all is done, Sync you iPad and your duplicates should have been erased.



Hope it works!