Integrated GPU runs at the same time with the Dedicated GPU.

Boot in to BIOS and see if you can't disable the iGPU. You should worry about temps especially with a gaming laptop. 80C is almost expected though in a laptop with an i7 playing games. I would run the laptop on a cooling pad if I were gaming on it.

Normal temps for a laptop with that kind of a cpu.

If this is a laptop with switchable graphics (Optimus on Nvidia, I forget the name on AMD), the this is normal.

Early laptops with switchable graphics had a physical switch or a BIOS setting to control which GPU was in use. Their drawback was if you switched graphics, everything running on the computer used the new GPU. So battery life plummeted when you switched to the dedicated graphics even if the computer was sitting idle with no game running.

Modern switchable graphics switch GPUs in software, and more importantly allow you to assign GPUs on a program-by-program basis. So your web browser can be using integrated graphics, while the game uses dedicated graphics. And during the few minutes you quit the game to tweak some settings, the laptop automatically reverts to using integrated graphics.

The way this is done is the integrated graphics always controls the screen. The dedicated GPU shows up as a co-processor. The game uses the GPU to render a frame. The frame is then sent to the integrated graphics for display. The dedicated GPU never controls the screen, only the integrated graphics does. (This can cause a problem with certain older or poorly coded games which stop searching for a GPU after finding just one - back in the days before switchable graphics it was reasonable to assume all computers only had one GPU. The first GPU it finds is the integrated graphics, so the game never finds and cannot use the dedicated GPU.) So it's completely normal for both GPUs to be active when gaming on a modern laptop.

Anyhow, for your temperature issue, that's actually a pretty good temp for a gaming laptop. But if you wish to lower it further, a lot of times the game does lots of extra work with the CPU even though the GPU is the bottleneck on framerate. If this is the case, you can try turning off hyperthreading in the BIOS if you have an i7. You can also disable turbo boost on an i5 or i7. Power options -> change plan settings -> change advanced -> processor power management -> maximum power state -> set it to 99%. If you want you can set the percentage even lower to limit the CPU's clock speed. You'll probably find that you can lower it all the way to 70%-80% with little to no effect on framerate because most games are GPU-bottlenecked.