Darn,

They forced me to install what was the current version of 1.0.0.38666 on Monday because last Friday's version 1.0.0.38600 caused them to disable my account. AND NOW, on Wednesday, the current version is 1.0.0.38690 ???

Most of the time there is no difference in the versions other than the version number itself. The Stamps.com programmers say that even though WinMerge indicates no changes other than version number that there are in-fact changes to the files and that WinMerge is not a valid utility to check for differences.