( And the other way round? Can I get the app-scoped ids (for apps I own) via the original user id. that would help too. I think the Business Mapping API (developers.facebook.com/docs/apps/for-business) may offer something like this.. – kolli May 22 '14 at 13:38.
Facebook Sign Up. Step 1: Fill in Application Form.
You must use your REAL name to sign up for Facebook. If you use a false name in your Facebook profile, your account will be terminated without notice because of violating Facebook’s terms and conditions.
If you were using the old Facebook ID, this change can cause big problems. Facebook says, "No matter what version they originally used to sign up for your app, the ID will remain the same for people who have already logged into your app.