Using two home health agencies. Any advice?

Why? You won't have double coverage and may get stuck with a bill.

Robinshor, we really need a lot more information as your title doesn't tell us very much. If you could elaborate, it would help us.

I assume you are able to get better hours or choice of caregivers by using the different agencies?
The only downside that I can see is that there will be no communication between the agencies, so you will need to be certain any problems that need to be addressed with one caregiver/agency are also communicated to the other.