What if user A and user B were drawing things that were supposed to coexist? Perhaps one is drawing the heart outline, the other is filling it in, etc. If ever

What if user A and user B were drawing things that were supposed to coexist? Perhaps one is drawing the heart outline, the other is filling it in, etc. If every potentially-conflicting action was followed up with a "which version do you want to keep?", it would get rather tedious. And I don't imagine an "AI" would answer that question 100% accurately either, but it would make it a less frequent issue.