There’s no benefit, currently, from having multiple GTX cards.
If you’re going to go a multi-gpu direction, you’re better off aiming for quadro cards - and I don’t know that I’ve seen any laptops with multiple quadros on the market these days.
I have the origin laptops with the single gpu’s and no complaints. We have some of the thicker 15" ones as well as the slimmer Eon 15" ones.
Edit: Forgot to mention the specs seemed to have changed on the slimmer one since we bought ours a year or 2 ago, so the new specs might not be great, I think its only a 1060 or something now.