As per conversation between Jeff Haagnestad of Exogal and myself he is strongly against doubling the umbilical between the Exogal products. He went into several technical reasons why it would not be good, and so I will not recommend it. I do not typically dismiss manufacturers' recommendations on such things.
I have been using the Comet alone with the Schroeder method ICs into various amps with terrific success. I am currently running sonicTransporter i7 and Signature Rendu SE into Comet and direct to various amps. Superb! (These have been reviewed for Dagogo.com)