Frank it is very unlikely that the lugs in that disconnect are rated for two conductors.
Part of 110.14(A) Terminals.
Terminals for more than one conductor and terminals used to connect aluminum shall be so identified.
So unless on the labeling of the disconnect you can find information identifying the terminals for more than one conductor you are stuck with one conductor per terminal.
You could also look on the labeling to see if a double lug kit is available.