Let your resin cure. Once that is done you can coat it with any other brand of resin. Cured resin is stable and non reactive.
When epoxy cures some waste products are forced out of the hardening resin and end up on the surface as a waxy ‘amine blush’. If you use multiple pours of the same brand of resin, and apply these at a time when the underlying coats have gelled, but not cured, then these amine waste products can be dissolved in the second pour, and be carried out to the surface.
But there is a limited window of time for this to work right. Miss the window and you just need to wait for a full cure, and sand or wash off the clear amine blush before adding more resin.
Epoxy Resin does not stick to the waxy layer of amine blush.
Hot soapy water and a stiff scrubbing removes this safely. Some people sand it off, but the airborne dust can cause respiratory problems.
You can get some compatibility issues between different brands of resins when one is poured over an uncured resin. Sometimes that is simply a trapped layer of blush.
But these compatibility issues are so varied that I don’t know of any list that says which are safe to mix. It is safe to apply a different brand over a cured layer, though.
In the event of incompatible reactions it is a tremendous annoyance to remove the bad layer of resin.