This sleight bears the name of the Chinese conjurer who introduced it to Western magicians in 1914, but the basis of the move is centuries old. An illustrated explanation of it was given in the 1779 Japanese book by Hose Hirase, Tengutsu (see Genii, Vol. 63 No. 5, May 2000, p. 14). Much of Japan's magic was imported from China, so it isn't known in which of these countries the sleight originated. But Hose's book presents the earliest known description. In the explanation given by Hose Hirase, the two coins that actually fall from one hand seem to come from both hands, one from each. In the handling done by Han Ping Chien, the coin or coins released from one hand appear to come from the other. While the concepts are quite close, there is a difference. Han Ping Chien may be the originator of the variation. If so, his variant was probably derived from the far older sleight.
Also see Han Ping Chien in Spectator's Hands.