The Cowboys have done a background check on Miami quarterback John Beck, but they have not had talks with the Dolphins regarding a potential trade for the 2007 second rounder, according to two sources. After signing Chad Pennington and drafting Chad Henne in the second round, Beck and Josh McCown are in a fight for the No. 3 quarterback slot. According to the sources, the Dolphins contacted the Cowboys - and other teams - about Beck shortly after coming to terms with Pennington.