As far as I know, the 530 CAN record two channels, but you have to watch one of them, or watch another recording. I believe this was introduced in a newer firmware update.
Please note that this is simply my understanding, as I do not have a unit to base my judgement upon.
The Motorola DCT6412 had the same problem originally, but has also since been fixed with a firmware update.
Motorola just likes to get the product to market, and then worries about features later, which gets the hardware in the hands of the customer sooner, but can be frustating for early adopters.