yes, but the current way, you have to buy two Tivos, and two subs.
that covers the cost of the Tivo(s).

Integrating two [analogue] Tuners into a single Tivo, plus software to control them both, plus other extras [like more memory etc], would make it uneconomic to do unless there was a large demand for them.

Better for Tivo to sell lots of single Tuner boxes...