I'm a bit confused about your reference to releasing scores.. If you complete a primary, the MCAT scores will be sent to the schools that you've indicated (and paid for) on the primary, as soon as the scores become avaialble. There's not "releasing" of scores, or at least no action needed on your part.
If you chose, say, 10 schools, killed the MCAT, and then decide to apply to 10 more schools, as soon as you add those schools to your amcas primary, they'll see your MCAT score too. May take a day or two, but it's pretty immediate.
Yes, schools see your MCAT before sending out secondaries, some schools screen before sending out secondaries and only send them out if MCAT score is at or above their cutoff.
I'm not understanding your reference to a "second set of scores". If you took the MCAT before and just retook it 6/13, hopefully you indicated this on the Amcas primary. If this is the case and you did NOT indicate on the primary that you are retaking the MCAT, I'd get on the phone immediately to the schools you'd selected on the primary, tell them you just sat for the MCAT. This is to prevent being screened out based on an old MCAT score. Or did I misunderstand what happenned?