Let's suppose that two developers each create their own app and each of them want to call it "nameApp". Can they both publish it on Apple App Store, Google Play Store and Microsoft Store?
In other words, is it possible to find two or more different apps with the same name on the well known app stores?
Not sure about Microsoft Store, but with Android and iOS apps are identified by app id. You can't have multiple apps with the same app id. The name string is more superficial, it isn't used as a unique key in the app stores - it's more of a visual thing client side.
EDIT: Looks like Google Play Store allows multiple apps to have same app name as long as they have a different app id. But iOS requires both app id and app name (but not display name) to be unique from other apps in the store. That's probably also why you see so many apps with super long, specific names in the iOS store.