Yes, all 10.x will skip the minor version in $installdir name and the registry keys so that they are all installed in the same installation location and are considered as updates. Only major versions are installed side-by-side. That is how installbuilder behaves.
The EDB Windows installer says it installs version 10.5, but once installed the list of installed packages (Control Panel\All Control Panel Items\Programs and Features) only shows a version of 10. This makes it quite hard for configuration management systems like Salt or Puppet to decide whether a minor version update needs to be executed or not. Because of this, Windows installers should always register the exact version number for the package.