I have a T7600 with 3x Quadro M6000 and I can use all 3 GPUs simultaneously without issue. At one point I did try to install a P40 but I couldn't get even a single one working. That said, since you are able to get 1 of them working, I see no reason that 2 can't work.
Do you have 2 CPUs installed? 2 of the PCIe x16 slots will only work with a second CPU installed.
The beautiful thing about open source is that if you feel something is missing or can be improved, you have the power to change it. Try fine-tuning a model. Although you may find that LLMs in their current state will struggle to do what you're aiming for. They're not really designed to always be truthful or act as a database of historically accurate facts. They may be able to play a role in a larger system that is capable of those things, but not alone.