I debated getting a 2 unit model about a month after getting the single.There are also 2 burner portable units. I have this
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I tested it vs my gas top and it heated up a measured amount of water in half the time it took my gasser to boil--4min vs 7 min.
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Wife decided we didn't have enough counter space. She also said it isn't that big of a deal cooking one pot/pan at a time.
If it was just me, I would probably go for a dual unit.