In dual mono, why does 200 become 400, but 250 becomes 800?

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If I had to guess, perhaps the 250 can actually deliver 400 W (into the same load as an 800) but is limited by the configurator whereas the 800 isn't. Presumably for marketing purposes there needed to be more clear space between the 400 and 800...so maybe the 800 is operating closer to the "real" limit than a 250.