Prior to Keyclone, with two windows open and moving the mouse between the two...
Ya I know, kinda funny...

My best combo of toons was BM-Hunter with Demo-Warlock.
I'd win maybe 1-3 matches and lose 7-9, starting at 1500 each week.
It was not a competitive team, essentially pet attack on each and SB Spam/Auto Shot focusing on one toon.

You'd definitely perform better with Octopus/Keyclone or Hardware boxing.

Two individual players each making independent decisions is too much of an advantage over your limited ability to perfectly coordinate the burst.
You'd certainly be better then some teams, but the highly rated teams with skilled/geared toons would own you.