What do you mean with "hub"? Are you talking about the Lutron bridge? If so, yes, you can have two (or more) of them added to Hubitat. I think there are some issues where Lutron won't let you register two to the same account, so you might have to figure out something creative (a second e-mail address?) there, but once you get them set up in the Caseta app, if you only use Hubitat to control the automation portion, it shouldn't matter too much.
You could also look into Lutron's higher-end solutions, with the next step up being RA2 Select. Caseta is supposed to cover about a 30 ft radius from the Bridge, with your first plug-in dimmer/extender adding an additional 30 ft. (must be placed within the 30 ft range of the Bridge), providing about 2500-3750 sq. ft. of coverage in total. RA2 Select is supposed to give about 5000 sq. ft. total, with the ability to use one "main repeater" (more or less equivalent to the Caseta Bridge) plus up to 4 additional "wireless repeaters," and repeating devices can have up to 60 ft between them (other devices still limited to 30 ft). As an added bonus, RA2 Select and higher let you use occupancy sensors--the one thing I think I miss from Caseta, but I don't really want to pay for more right now. And maybe you don't either--a second bridge could effectively help in your situation if all you care about is Hubitat integration. Just thought I'd mention this anyway!