I can't reproduce this. Are you sure you're not pasting the same release notes in multiple versions? Because wyUpdate compiles a list of everything that's changed in your software from the version the user has installed to the current version.
For instance, let's say a user has version 1.0 installed, and you've since released 1.1 and 1.2, When the user updates your app the update information they see will look like this:
1.2 Release notes
1.1:
1.1 Release notes
That is, the latest changes will be showed first followed by all changes that have happened since they last updated. In other words it's not limited to just the latest release notes.
Does this make sense?