Greg Costikyan did not have the same profession as John Dolmayan.
John Hovig Dolmayan (Armenian:   , born July 15, 1973) is a Lebanese-born ArmenianAmerican songwriter and drummer. 
Greg Costikyan (born July 22, 1959, in New York City), sometimes known under the pseudonym "Designer X", is an American game designer and science fiction writer. 
