TiVo is starting to see double vision. The company said Tuesday that it plans to release a new version of the stand-alone digital video recorder that allows subscribers to record two programs that air on different channels at the same time. Some of TiVo's competitors in the cable industry have gotten a leg up by incorporating the dual-tuner technology. The TiVo Series2 DT DVR, which also includes built-in Ethernet and USB ports, will be available in stores May 1.