How do I delete photos that are repetitive that was automatically sent from my mac to my ipod nano 7th generation? I cant figure this out and it is frustrating. I have thousands of photos on nano because it downloaded all photos 4 times or more.

I bought a new ipod nano and it automatically downloaded all of my photos from my mac computer some how. On my computer someone accidentally downloaded the same photos 4 times so I have thousands of photos replicated ones, on my nano. I cannot figure out how to delete the replicated photos from my nano or my computer! I tried to go to itunes and was going by directions from the user manual for the nano 7th generation and it is hard to find where to click in itunes based on the manual. It is confusing and frustrating. Can anyone tell me how to delete the extra copies of the same pics from my nano that is easier than trying to follow the manual? help!! Thanks so much

Betsy