What exactly do you mean by "identity changing"?
If you're doing something that causes the BOINC server to think your computer is a different computer, that's likely going to cause problems. Those problems likely include abandonment (complete loss) of existing tasks on the computer.
Supposedly there's a safe way to run multiple instances of BOINC on a single computer, but I've never tried it and can't provide any guidance for that.
This is definitely not a case of multiple instances of Boinc on the same computer. As I watch the time remaining estimate I think it is either the inability of Boinc to make anywhere near a correct time remaining OR it is a case of the wu backing up to the last point where it can start again. In wus other than GFR I noticed that when work is suspended and then restarted the remaining time will back up a few minutes or so but will quickly catch back up. Maybe the GFR wus don't establish a point of reference very often that it can return to and a whole series has to begin over.
I am leaning toward Boinc as the problem.
At the same time it would be interesting know how the wus know where to restart after a suspension.