It certainly did when I tried it yesterday.
ETA: Twice: once in each submission order (“Reported” post followed by report, and report followed by “Reported” post.)
Your information appears to be completely theoretical.
Double posts can happen when you get a server hangup after submitting and it won’t reload the thread. You’re not sure it went through and resubmit.
I reported one of those damn reddit link spam posts just today. By making a “Reported” post to the thread followed immediately by sending a report I’d already written from a separate tab. The two entries were sent about 5 seconds apart. It worked fine.
The only reason I used two tabs was that I started writing the report post before I remembered I needed to send the “reported” post first. So I re-opened the thread in a second tab to do that.
Far be it from me to assert that the SDMB is always glitch-free. We both know better than that.
But my knowledge isn’t just theoretical. TPTB say it works as I’ve described, several other posters in this thread say it works that way for them, and I’ve had it work that way for me on many occasions up to and including today.
I will at some point in the very near future for absolutely sure report this here thread.
I’ve done this many times (posted “report”, then actually reported it) and it has worked just as described. I’m not sure why yours didn’t work, but that’s not been my experience.
Feel free to report my post as a test if you’d like to try it.