There are a few dedicated twin sites, but you'll have to search them out AYOR. The problem is that several of the more famous pairs, especially those who worked in 1970s porn and who modeled for Bruce Weber during the 1990s, were underage, making this a problematic area, since almost all the sites carry images of at least one set of such twins.

To make up for this, a selection of completely legal twins from around the globe in alphabetical order of surname (how anal am I?).

1) Jirka and Karel Bártok

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, video clips

2) Kyle and Lane Carlson

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17

3) Alex and Alan Fisher

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20

4) Daniel and Jacek Gutszmit

image gallery

5) Jean and Daniel Lautrec

image gallery

6) The Mendez Twins

1

7) The Ontami Twins

1, 2

8) Nicolai and Boris Otov

1, 2, 3, 4, 5, 6, 7, 8, 9, 10

9) Dean and Dave Resnick

1, 2, 3, 4, 5, 6, 7

10) Derek and Drew Riker

1

11) Rodinei and Rodrigo Santana

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22

12) Justin and Ryan Woods

1, 2, 3

Anonymous but worthy of mention

1, 2, 3, 4
(1 has subsequently been identified as Spaniards Oscar and Gabriel, billed as The "Odyssey" Twins; 2 and 3 have subsequently been identified as Canadian-born 1980s porn stars Joe and Justin Cade). Who are the guys in no.4?