If 2 people are working on a roadmap at the same time, and one moves an epic to the top and saves, is the second user warned that their date is stale? Is it just that the last person to save wins?
If two users are editing an Advanced Roadmap at the same time, when either user presses the "Review changes" button they will see a warning about concurrent editing and be directed to refresh the page. No user takes precedence here, both users will get the same message.