DALLAS—Yes, people across North and West Texas are seeing double. That’s because TXU Energy’s cash back offer has just, literally, doubled for residents across the Oncor service territory. Through March 31, 2011, new residential TXU Energy customers across Greater Dallas-Fort Worth, Midland-Odessa, Sherman, Tyler, Waco-Temple-Killeen, and Wichita Falls can earn 6 percent —up from 3 percent —cash back loyalty ....