What kind of dimmer pack is this? I sounds like one of the el cheapo dj models. The instructions read, "Just plug it into to different outlets on different breakers and you are good to go!" If you are modifing it for fixed wiring you are probally violating it's listing (if it is not an unlisted taiwan knockoff).
Most dimming kit has OCPD rated at 100% with the assumption that in a large installation that all dimmers are not pulling 100%. For example a 96 dimmer rack with 20 amp dimmers can be feed from a 400amp three phase service as per the manufacturer.
As for your dimmer, if you open it and take a look, it is two seperate devices. Each 20 amp dimmer has a scr or two, a couple of chokes and a firing circuit. Technically, you could load the each dimmer up to 100%, but if you plan to do this full time the entire installation needs to support it (100%rated OCPD in the pannel). Do not put bigger breakers in the pannel, stick with the 20amps.
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