Yes, the DB is shared by all of them.
That is not a problem.
I am using django-social auth for my app.
The problem occurs when I have say website.com/something as the redirect_uri on twitch.
Now, if I login using twitch on localhost, I get redirected to website.com after login.
This is creating a problem.
Google allows having multiple redirect_uris and thus, this is not a problem with Google.