Two Bobby Darins could be duking it out for attention, thanks to a pair of rival movies about the 1950s singer (“Mack the Knife,” “Splish Splash”) that are in the works. Last month, reports Variety, Dick Clark Productions signed a deal with the late actor/singer’s son, Dodd Darin, for a Bobby Darin feature or TV movie. Dodd, however, is the author of the 1994 book “Dream Lovers: The Magnificent Shattered Lives of Bobby Darin and Sandra Dee,” upon which producer Andrew Friedman will base his own movie. In addition, Friedman claims “exclusive” rights to use certain Darin songs in his picture.