Duplicate photos in my Photo Library on my iphone 4s?

So I just update my iphone & when i plugged it into my computer to sync, it re-synced my photos & stuff. Now in "Photo Library" album (which I assume all iPhones have) each picture has a duplicate? So instead of 300 photos, theres 600. Anyone know a way to fix this? I didn't have this problem before.

*Note: I just updated my phone today with the ios 6 update.*

I had another folder to sync photos to, and moved everything out of it so the folder was empty. Synced the phone and found one set of duplicate photos were still on the phone, so I found the folder labeled "iPod Photo Cache" and deleted everything out of it. Synced again, phone was empty. Moved my photos back into the folder I'd been syncing from, and now there's only one set.