The ampacity table is for 3 current carrier conductors in the conduit. I do not believe we are allowed to rate up for only 2 current carrier conductors. But it is good point, I will look to see if NEC allows any up rate.
For quick conduit fill I usualy use: https://www.southwire.com/calculator-conduit
For quick conduit fill I usualy use: https://www.southwire.com/calculator-conduit