To start, lets clarify that an online agent in EMMA can only provide an Online Activation Code, they cannot generate it.
Once the OAC is given, you gain access to that Applicant's online environment for those cases.
If this was a completely different immigrant, the biometrics notice in the online environment would've had a different A-number and different name/DOB.
Seeing that this isn't the case, obviously USCIS somehow assigned a duplicate A-number for the same person.
To clarify, the keyword you highlighted is "eventually",, regarding the timeframe someone getting their Biometrics notice.
You didn't quite articulate what you meant with the highlighting, so let me just make a general statement: Biometrics appointments for AOS are often scheduled 3 week out, but I have seen the occasional 2 weeks.
This is a very tight timeframe for some, especially considering mail can get lost. It is much safer to contact the EMMA representatives to ask for your OAC as soon as possible, so that you may access the digital version fo the biometrics scheduling letter.
And yes, in case you know, the biometrics notice in the online environment is not exactly the same as the physical one mailed to you. However, they accept them as Application Service Centers, something I have done personally.
If they receive a physical biometrics notice with the correct A-number, there would be far bigger implications. The existence of two biometrics for the same person, differing only by A-number, would mean there would have to be two duplicate AOS filings for the same person, with duplicate biometrics notices and duplicate MyUSCIS-environments. All differing only in the A-number.
Furthermore, OP mentioned that the AOS NOA1s did show correct A-number. Therefore, if the Biometrics notice is visible for them in the online environment under the i-485, which does have the correct A-number, clearly the two A-numbers are connected to the same case. This means that the above theory of "everything might be duplicate" doesn't fly.
Lastly, quick search on Google already shows that USCIS does assign new A-number to people at times, for whatever reason or non-reason. There is no need to further double-down on your stance by digging into a deeper complexity.
The amount of comments someone has on a single forum cannot be directly equated to knowledge. You have what most would consider a substantial amount of posts on VJ, yet I find your knowledge on the whole lacking and bordering on misinformation.
Also, what is your experience with e-files/IOE-cases? Do you keep up-to-date with developments?
I have also seen you claim in a different thread that people that filed on paper but get an e-file (IOE) are somehow not elligble to respond to RFEs via the online environment, which is also not true.