You’re on the right track for a Part 91 operation, but for Part 135 you need to also consider the Part 135 MOS. For your particular question, have a look at Section 11, especially 11.09.
Essentially yes, you still need 2 receivers in the aircraft, but the requirement is actually that you ensure you have redundancy, rather than telling you exactly how to achieve it.
If you are actually working for a Part 135 operator, their exposition may include company procedures will would hopefully cover the legal requirements in a more user-friendly manner.