I think that moodle don't change the profile. Only one user.
In our moodle we have a security problem. Sometimes when two students logged at the same time in our moodle, one of them can begin to work with the account of the other. In this case he can change the profile of the other. We have a problema like this, but we can find who was the student that change the profile of the other find in the big registry of moodle.