If I understand the situation the applicant is trying to get a copy of a letter by having the writer submit to a second "job" that is basically sent to the applicant directly. First of all, regarding the confidentiality rule. While the applicant gives up the right to demand to see the letter, the letter writer is perfectly free to show it to the applicant if they choose to. Most professors do not do this or are aware of the option. Additionally as @Goro or
@gyngyn have mentioned in the past, about 20% of letters are truly outstanding, 10-20% are truly low evaluations, and the 60%-70% in the middle run from above average to average to fair. It is, in my view not the most impactful factor in an applicant review. Rarely, very rarely, is there a strongly worded, specific issue, negative evaluation that blatantly states not recommending an applicant for medical school. Others that are negative for the most part, really aren't anything unusual to an adcom. They read usually more as a tough professor than anything else.
As for the situation here, the applicant is exposing him/herself to an unethical act that can follow you up thru being awarded your MD. You are violating at least 2 direct agreements on your letter request and on AMCAS primary in this regard. AMCAS has a strong incentive by the 130 odd schools that use them to keep the confidentially solid as well as the letter services to keep their contracts in order. They are audited randomly and would initiate investigations fairly quickly. Most of these are simple and cleared up without any involvement with applicant. Things like a letter writer submitting more than 1 letter, say MD, DO, and PA may be enough to flag and review.
The real issue is the risk; if considered a violation, you would likely be banned from using AMCAS. End of story, do not pass go, do not collect your MD from an American school ever. While I am on the subject, letters that reach schools will more scrutiny as you move thru the process. Professors get called for simply thing like no letterhead. If a school suspects fraud, you would be dropped and likely reported. Let me just add that if any ethical situation in the application phase is discovered, even after you have been admitted, you can be thrown out. Recent court case on this strongly supports schools in this action. You would have loans outstanding that you could be sued over for fraud by the Federal government. While unlikely, you could get Federal criminal charges for fraud (I know of at least 1 case of this). It would be an interesting set of circumstances to explain when asked by your cell mates in Federal prison when they ask "What'cha in for?"
In sum, the obsessive compulsive fear and stress that this process brings upon premeds is no reason to risk it all over at worst a possible weak letter
https://www.aamc.org/download/272452/data/coabulletin1.31.12.pdf
The release of confidential information in an evaluation letter to an applicant, no matter how inadvertent, can negatively impact the applicant’s relationship wit h both the letter writer and the medical school to which he/she is applying and undermine the candor with which letter writers are likely to convey information in the future.
https://www.aamc.org/download/332578/data/lettersguidelinesbrochure.pdf
https://www.aamc.org/initiatives/admissionsinitiative/letters/332572/lettersofevaluationguidelines.html
https://www.aamc.org/students/advisors/amcas-advisors/370390/amcas-letters-advisors.html