"Siamese Twins" is the old, un-pc term for conjoined twins. Named after brothers Chang and Eng Bunker (1811 – 1874) who were born in Siam (now Thailand). I don't think the girls in this vid are identical twins - fraternal, maybe.
Siamese tvins?. That means tvins that are grown together. tvins that are look alike are called Identical Twins and come from sp spermcele in one egg. But I dont know if you meant siemese cats though.