Copied Folders Are Larger Than The Original Folder?

This issue is absolutely frustrating. I recently did a reinstall of Windows on my Gateway LT20 laptop. I did so from the recovery console (Press F8 at boot, restore from recovery partition and retain user data).After the reinstall, I decided to Backup the rather large collection of personal files that I have on the C: drive. (Actually, this would be a second backup) As I began copying folders over to the external drive, permission dialogs would occasionally pop up......very odd as I am the sole user of the computer and am the admin. I noticed an "account unknown" set as the owner in the security tab and I figured that it was because the files were carried over from the previous install and the unknown account was just my admin account from before. So, I took ownership of each folder (and selected "replace owner on subcontainers and objects). Alas, I was still getting the UAC permission dialog when copying some subfolders. I said 'screw it" and just clicked "OK" to get on with the backup. This is followed by a "do you want to merge folder A with folder A?" dialog.

And so the folder begins copying to the new drive with it's subfoldersHere's the weird part:After I click "OK" the displayed amount of data left to be copied shows zero.....but it keeps copying data. And it just keeps going. The status bar of the copy dialog box shows a smaller amount of data to copy than there actually is in the source folder. And by the time the main folder is done copying, the resulting folder is larger than the original O-o What the deuce?! The properties dialog box tells me there is more files present than what's in the original folder.I.....I just want to copy my damn music and photos to a portable drive. Why do you curse me computer gods?!! *shakes fist at sky* I'm very confused and want to know why and how a source folder that is 18GB turns into a folder that is 28GB when copied.