Do you also have authentication enabled using App Service Auth/Easy Auth (this: https://learn.microsoft.com/en-us/azure/app-service/overview-authentication-authorization) - doing so could result in you having app registrations with the same name as the web apps, if you just accept the values that setup gives you as given.

To answer your question, no, a managed identity does not generate an app registration that you can manage; it is only an enterprise app.