Strange email sign up in android app (Internal Test)

I have an android app in Internal Test, so only those who are entered with their email among the testers can download it. It happened to me after the publication of the recent version to notice the registration (in the connected mysql database) of an email not present among those of the testers. The structure of the email is of the type elgoogclass (a number) @ gmail.com. Is it possible that it is a test by google even though I have not entered any test credentials in the Pre Lunch test? PS. I watched the videos that the google bot does in tests but it does nothing but write "text" in every field of the registration screen