Brilliant Diamond Shining Pearl Count as the Exact Same Game According to Nintendo

Let me explain. I own a Switch and a Switch Lite. I also own the digital versions of BD and SP and have them downloaded on both and I understand Nintendos whole gripe about not letting you play the same game on two different consoles at the same time, but I can't even play Diamond on one console and Pearl on the other. If I try opening the OPPOSITE two games on my two switches, without fail, onw of them will tell me the title is unavailable and being played on a separate console.

Am I missing something and this is intentional? Or is this just an oversight? Because this never happened with Sword and Shield.