VALLEY MILLS, TXAn AKC certificate of pedigree proves conclusively that Duke, a 2-year-old Rottweiler from nearby Rock Springs, is the puppy daddy of Skipper, a Rottweiler born July 20, Cloverleaf Kennel sources reported Monday. "Duke can bark excuses all day and night, but this pedigree proves that Skipper his," said attorney Seth Freidman, who represents Ginger, Skipper's mama. "Duke should be responsible for Skipper's upbringing. I'm sick of hearing that it's a male dog's nature to seek out multiple breeding partners." A spokesperson for Duke said his client was lured by Ginger's promiscuity, insisting that "everyone know the bitch have litters by three different dogs before Duke."