Notice that the byte counts are exactly the same, it's only the conversion to megabytes that has changed.

For whatever reason, some manufacturers go for 1000 bytes in a kilobyte, then 1000kb for a megabyte. It should be 1024 to be technically correct. Based on the byte counts, neither of the roundings into mb are correct... it should be 139mb plus a handful...

I wouldn't worry - I've seen it quite alot over the years, although I don't know alot about macs....