My favourites of recent years aren't in your list. The British twins Chantelle and Chloe Stevens. Few clips of them here: http://www.twins-sex.inxstasy.com/
But all time favourites gotta be Brooke and Taylor Young who starred in Teenage Twins. Those two got fruity together. ^^
I seem to remember a DVD where a pair of blonde enhanced twins did ATM (with one twin sucking her sister's ass juice off a guy's dick). I think they've appeared on Howard Stern.