Well you have two options. You can dance two separate dances and choose a special song for each one or you can begin dancing with your dad and have your stepdad cut in about half-way through.
Talk to your band/DJ to find out what they recommend. Two special dances plus the groom and his mom’s dance make about 8-10 minutes and to be honest after about the first 30 seconds no one is really paying attention. To keep your guests in the party mood you may want to choose one song.
But if you’d prefer two, break up the dances. Share the first dance with dad between the first and second course and the second dance with your stepdad between the second and dessert. Or vice versa.