Hi @sovanyio
Thank you for your PR. I'm taking a look a it when i have some free time.
I encountered the same problem as you with my two cats, who weigh almost exactly 5kg, give or take 100g.
The solution I found was to set the lighter cat's profile to 4.7kg and the heavier one to 5.3kg, and most importantly, disable automatic weight updates.
But the other problem was that the PuraMax scale isn't very accurate.
I switched to the Purobot Max Pro with the camera, but even then it's not perfect because my cats are in completely different colors, and the AI makes mistakes 
I think frigate is the best alternative !