Technically, not all reports will be handled the same even if it's for the same post. Since, the reporters might be reporting for a different reason to another. One could be reporting for the wrong section, but technically not be correct, and another might be reporting for a duplicate thread, and could be right in doing so.

So, it's case by case. However, as correctly pointed out, generally if they're being reported for the exact same reason they will all be handled the same. Sometimes, a moderator might just delete a report, and not bother checking individual reports of the same report, since they're handling it in the order it pops up in their report queue. It's probably best from a moderators point of view to check all duplicate reports for the reasoning's, but unless you have a user script to bunch them up, this isn't always obvious since by default the report queue doesn't behave in such a way.