Every application’s files are separate, unless you duplicate the application. But many of the contained files could be duplicates. My Mac has 80 copies of the Sparkle framework, multiple copies of Electron, and so on.
There’s also just badly designed apps. For example, iMazing downloads .PNG files for each app icon, and saves them separately for every version of the application. It never purges them! So I only have 261 apps in the iMazing library, but there are 17,359 icon files. It appears that most of them are exact duplicates.