With a fresh copy of your PHP sample scripts, I am getting the following results:
1) If I edit an email address (and any other field) except a list, everything works fine. The record is updated successfully.
2) If I edit an email address (and any other field) including a new list(s), the email address is added as a new contact instead of updating the original.
I struggled with trying to find out why this was happing on my website with my custom code, then realized after troubleshooting that the same issue was happening with your sample code.
Any suggestions as to why this is happening will be greatly appreciated!
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