There was an AU where eggy took the crystal of creation and made another one.
But, a huge thing related to the crystals is balance, so the moment he made the second crystal that broke the balance and the multiverse was consumed by light
It works the same the other way around.
In another AU beldum breaks the crystal of creation during his final battle with the collector, and the multiverse is consumed by darkness.
So the same thing would happen if you had a second crystal of destruction.