As vmroyale noted: http://kb.vmware.com/kb/2003813
You get what you had when you do a straight upgrade. You could try using the datastore browser to download the VMDK-flat file to your workstation / USB drive, etc.
If I was going to guess about the "how" I would say that some file/set of files were allocated simultaneously which created the overage. Also, if the block indirection was slightly more efficient than promised perhaps that would account for the 2 MB overage you are seeing.