It is not random. It is consitently picking the same document on all servers that have seen the same changes. By default it picks the one with the most changes. That consintency ("the same" part is very important) it means if you replicate and bring in some conflicts, both sides will show the same state. So you won't randomly after replicating A to B, and B to A see document 1 as the winner on A but 2 on B. They'll both pick 1 or 2. So both would settle on the same state.

Also it doesn't delete or remove conflicting siblings, it is very good about not doing that to user data. Users only know exactly how to solve particular conflicts.