Did you accidently make a typo saying "greater power consumption for parking mode" and also "less power consumption in parking mode"? (or am I interpreting your intent incorrectly?)
Not exactly a typo, I think on the "less", I was thinking of the advantages of a dual channel dashcam! Now corrected in my post above.
Thanks. I noticed you didn't mention heat, is that not really a differentiating factor?
For most people, heat is not a big issue with either 1 channel or 2 channel dashcams. Depends where you live of course, but the 2 channel dashcams do tend to have better cooling, and maybe more efficient electronics, so your maximum temperature is only going to be a few °C different, maybe only a couple. There have been a few multi channel dashcams that have struggled with heat in hot places/weather, but modifications and firmware updates tend to sort them out after a couple of production runs.
If you are in Death Valley then the single channel dashcams will have difficulty too, however they don't tend to have self protection with high temperature shutdown, while the 3 channel ones generally do, so single channel might actually be a disadvantage there.
The biggest problem we see with heat tends to be the dashcams with lithium batteries, often Nextbase ones, and I get the impression that there are more single channel ones than dual channel ones that have problems, probably because they sell more single channel ones. So don't get a dashcam with a battery, single channel or multi-channel.
I don't think you should treat it as a major deciding factor unless you live somewhere very hot and want to use parking mode in the heat, or you are looking at a dashcam known to have heat issues.