What you see are the so-called global and app-scoped user_ids. If you’re using v1.0 of the Graph API, the user_ids will be global. If you use v2.0 they will be app-scoped, as in your first example.
It’s all in the docs: https://developers.facebook.com/docs/apps/upgrading#upgrading_v2_0_user_ids
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solved Facebook user ID. Which one?