One way around this (from the developer's side) is to federate together different identities for a user using something like dex [1], and segregating your login

One way around this (from the developer's side) is to federate together different identities for a user using something like dex [1], and segregating your login and signup paths, so attempts to login will never create a separate account. [1] https://github.com/coreos/dex https://github.com/coreos/dex