correct permalinks

Hi guys, looking for some advice on permalinks.

I’m creating a new image gallery site where the user will be able to download image packs, will be 140+ posts. These image packs all have and same name i.e

graphics pack 1
graphics pack 2
graphics pack 3

I’m a little worried about the dupe urls i.e
http://www.site.com/graphics-pack-1
http://www.site.com/graphics-pack-2
http://www.site.com/graphics-pack-3

Is there some permalinks structure that will help make these urls a little more unique? Don’t really want to have dates in there.