I have a weird issue. I created two games, exported them both as offline installers, and they both install fine. Issue is, if I have one installed and I try to install the second, it’ll install over on top of the first and uninstall the first and vice versa.
Assuming you are using the automatic export option (one-click packaging), there is this warning on the export screen alerting you about the project name. Have you checked if the internal names of both projects are not the same?