EGPU GTX 1070 and GTX 1070 Max-Q run in SLI?

I have a Razer Blade 15 Advance with a GTX 1070 Max-Q from 2018.

For test purposes, I ordered a Razer Core X to see how a normal GTX 1070 performs, as I have one available here.

When I connect the graphics card via Thunderbolt 3 everything works as normal.

In the task manager I see, for example The 1070 Max-Q in the laptop is no longer busy, but the GPU memory is displayed with 16GB and as common GPU memory just 8GB.

However, if I want to play something, then the performance of the eGPU is subterranean, so that's way below what a GTX 1070 has on it and well below the performance that the Max-Q variant gives. (In Monster Hunter World for example ~ 70 FPS with the Max-Q vs. ~ 20 FPS with the GTX 1070 as eGPU)

I know that Thunderbolt 3 throttles the performance, but not so strong? The monitor is also connected via the eGPU.

Could it be that the GPUs somehow run in the SLI, as it somehow, are the same GPUs somewhere? Has anyone made similar experiences and there are solutions proposed?

With such a loss of performance, it would not be worthwhile to upgrade to a stronger graphics card than eGPU at some point.

In SLI the two cards are guaranteed not to run. This would require a connection via SLI Bridge.
The VRAM does not add up, neither in SLI nor in combination of eGPU and internal graphics card.
The performance loss with Thunderbolt is already relatively large. The newer mobile graphics card is not all that bad compared to its predecessors.