well, I think It's not...
Backeuped one is updated with new one only when the file size lower than that amount of size..
furthermore, i checked the file changed with new, by opening it.
if it's permission issue I think It's impossible even when the file size is lower than 2.1gb.
Defaultly I'm adminstor user.
I tried to test it by executing TVP with admin authority once.
Also,
i tried it when there is no backuped file with over than 2.1gb tvpp size,
If it's permmission issue, and if there is no backup before, It have to make backup file.
but it doesn't...