Yea I'm so confused I was legit sitting here like am I doing something wrong by doing this twice? I just sent the transcript request form to my registrar too ...
AADSAS needs to standardize transcripts to save adcoms a ton of hassle. Different schools use different scales, grades, etc. Typing it in and categorizing it allows for a simple interface that is the same for every applicant. They have to duplicate the transcript somehow, anyways. It has to be sent to every school you apply to. I'm sure there are rules about duplicating an official transcript.
Also, they don't have the manpower to handle transferring every applicant's info over themselves. It makes more sense to have the applicants do it.
So I guess the official transcript is just there to make sure you're not lying about getting an A in that organic chem class that you actually got an F in?