Today, this question was migrated from the main site to Database Administrators. Before migration, it had two comments; one simple one about being better suited, and a more elaborate one which happened to link to a specific answer on dba.se. (I've included screenshots for those < 10K in case it gets deleted on the source site.)
When the question was migrated, only the top comment remained (which I promptly deleted):
I'm pretty sure this is not how this is supposed to work. Either only the first should have been deleted, or at worst, they both should have been deleted. But I don't know exactly what the algorithm is or how these auto-delete decisions are made. In this case, it back-fired - deleting a useful (IMHO) comment, and leaving behind the redundant one.