I believe the OP is asking if the medical school adcom can see undergrad applications that have been submitted to same parent university. And the answer to that is only in extremely rare instances.
2011 has come back to haunt me
There was a thread in the past few months where an acceptee to a state med school who had previously applied to (but did not attend) associated UG school and who had described some HS disciplinary issue was now required by medical school to get letter from HS for "good standing." This was the only time I heard of a medical school reaching back to UG which in turn reach back to HS. My guess as a state university and having discipline issue, they were required to follow thru. Again, possible but is a rare occurrence