Do what? Pull out the old app and compare? I doubt it. They have thousands of new apps to deal with - hard to believe that they want to bother with comparing an old app to the new app.
As I said in a prior post, if the app has "improved" in the area of GPA and MCAT, that will be self evident from the new app alone (new MCAT date, new courses reported in the preceding year). Same thing with ECs - are the dates current, or did the applicant last volunteer at a soup kitchen over a year ago. No need to compare it to the old app to see if it has changed or improved - it will be evident in the new app.
The new app will stand, or fall, on its own merits.
And I believe
LizzyM said that her school doesn't do this (the pulling out of the old app, etc.). Maybe she will chime in here.