The Captain Sim 777 doesn't have any models that use the RR engines, so there is no need to buy that one. As for the TSS 777 PW and GE sound sets, this from the 777-200 >> Overview: Authentic sound set (TSS $12.99 value)
So as you can see, Captain Sim provide a set of engine sounds done by TSS, but I don't know if it's the full TSS 777 engine sets. I would assume that it is if it has a value of $12.99.