Someone in the pre-allo raised the same issue and here is what I said then
I am not going to cover all the 4 major areas that I feel this issues raises (ethical, legal, psychological, practical) but I will mention a few points.
***Ethical: The intent of applying to medical school is be accepted and attend. That is certainly held by adcoms across MD and DO. It would seem apparent to all involved in this thread the intent/plan here goes against that implied ethical design. It would seen that a blatant attempt to push ethical boundaries would be inappropriate some entering the field of medicine where ethics are highly valued.
***Legal: When you defer, you are signing an agreement that states you will not be seeking acceptance at another program. Most of those agreements are general enough that it will legally cover ANY other medical school or academic program. While it is unlikely you will be sued, it is most likely that DO school will notify AMCAS on this issue. But they are separate systems you say. AAMC and AACOM have been working together since 2000 towards what was originally called Physician2015. That project resulted in the MD/DO Residency Match merger. One of the reasons AACOMAS has recently upgraded their application system was to be able to more easily interface with AMCAS/AAMC. Both the formal networks, such as most DO schools have the National Acceptance Report, and the informal networks across schools, an applicant is taking a huge risk in doing the idea of the OP.
Well, once you are in MD school, there is no problem, right? Your minimum of 3 agreements (AMCAS, Secondary, Acceptance) have enough language to cover any unethical issues in applying up until when you are awarded your MD. A school can not only dismiss you at any point, the the federal government will sue you for civil fraud, where immediate payback of any loans, or at least in one case Federal Criminal Case for fraud against a dismissed student. Be interesting the story you had to tell your cellmate when they ask, "what are you in for?"
***Practical: As has been mentioned previously in the thread and as I advise students who have a desire to attend a specific set of schools is just apply to those schools on the first cycle. A year of working that that makes an applicant reconsider what he school he/she is willing to go to .
***Psychological: the need for the OP to have a "safety" spot for something he really doesnt want smacks of lack of confidence, a form of desperation to make sure he has a spot somewhere, and a somewhat devious thought pattern to get around the system. It really behooves the OP to examine weather he wants to be an actual physician or simply to have the letters "MD" after his name.
On a very personal note, I find the original poster's concept wholly unethical, devious and scamming at its core, and shows a lack of personal integrity and commitment. Would you want to be treated by a physician who shows these traits? If not, then why do something like that to become one.