There is not a 'fix' for this, this is by design. At the end of the job AppAssure and Rapid Recovery will open up a snapshot on the VM as a last step.
This is done so that if a user powers up the VM to test it, those changes/actions are stored in that snapshots and upon the onset of the next virtual standby pass, that snapshot is reverted (thus all the modifications are removed) and then deleted, and new one opened.
This is done so that the virtual standby VM is kept 'the same' as the source.
Every time that you power on a machine it is modified on the block level - whether you make a change or not, the blocks do get modified.
You can see these actions through vSphere if you open up the console and kick off a virtual standby task.
Also note that a snapshot is thin provisioned so your hypervisor will show an additional amount of provisioned space, but not allocated space.