Slingbox with Dual Tuner Tivo

No. The slingbox uses the output of the TiVo to stream (The same output going to the TV). TiVos cannot output two different video streams.

The only such box I know of that does what you want are the Dish Network (now rebranded as just "Dish") SD and HD 2 tuner 2 TV experience boxes that allow for the option, at the press of a button, of each tuner being used independently as well as accessing all DVR content independently and at the same time as the other viewer--essentially a completely independent TV experience. But, of course, that would require subscribing to Dish Network--oops, I mean Dish, and that may not be an option for you.