Although the fingerprints of identical twins are more similar than most, they are not identical.
More Info: One of the reasons for this is that while in the womb, twins obviously occupy at any one time different corners of the cavity. This, a 2008 study found, is enough to cause subtle differences in the ridging of their skin and fingerprints.
A pair of identical British twins can actually be historically linked to the decision by London’s Metropolitan Police force to institute a system of fingerprinting in the first place. Albert Ebeneezer and Ebeneezer Albert Fox, born in 1857, were notorious scoundrels. Over the course of their lives in Stevenage, England (they died in 1926), they were repeatedly arrested for poaching. However, because they liked to split up and always vouch for each other, law enforcement authorities had trouble managing the pair’s illegal hunting activities, despite the fact that they were convicted approximately 150 times of the crime of illegal hunting. Finally, London police commissioner Edward R. Henry was inspired to institute a system of fingerprinting, in part by the constant humiliation suffered at the hands of the Stevenage duo.
Less well known than the fingerprint but equally distinguishing, even in the case identical twins, is the palm of their hands. The University of Wisconsin recently became the first institution in that state to implement a palm scanning system. Called Secure, Accurate, Fast and Efficient, or SAFE for short, the devices can identify individuals based on the pattern of veins and blood flow in their palms. The palm print is different, even for identical twins. Palm-vein scanning is relatively new, but according to hospital officials, the mark of its potential is that it can distinguish the same sort of minute differences evident in the palms of identical twins as are in the tips of their fingers.
New York Times – “Twins and Fingerprints”, October 5, 2009, Retrieved November 4, 2010 from http://www.nytimes.com/2009/10/06/science/06qna.html?_r=1
American Heart Association – Mechanical Control of Tissue Morphogenesis, 2008, Retrieved November 4, 2010 from http://circres.ahajournals.org/cgi/content/full/103/3/234?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=embryos&searchid=1&FIRSTINDEX=0&resourcetype=HWFIG#R11-175331
Wisconsin Radio Network – “UW Health Introduces Palm Scanning”, October 27, 2010, Retrieved November 4, 2010 from http://www.wrn.com/2010/10/uw-health-introduces-palm-scanning/