The GPUs have no bearing on how Corona works, unless you have the NVIDIA denoiser in use as you mention. Best thing is just not to use it on a card like the Quadro, it might work but it will be slow, cause lags and hangs on the computer, etc. (I have an older 680 card, so I don't use the NVIDIA denoiser for that reason, and I stick with the High Quality or Intel denoiser for finals). As a note, the denoiser will only ever use one card, so installing 2 will not give you any benefit (and may in fact confuse the system as to which one it should be using), so definitely go with just one card.