Two Lots of Wallpapers?

I updated to Android 6 today. All seems well except when I tap and hold my home screen I get this:

'Choose wallpaper from'
Wallpapers
Wallpaper
Live Wallpapers
Photos

The first option contains one new coastal wallpaper along with my old Android 5.1.1 wallpapers. The second option contains the rest of the Marshmellow wallpapers. Why have I got two lots of wallpapers. How can I remove one?

Thanks.