[Python] Understanding and Fixing the regex?

I have a regex on my input parameter:

r"^(ABC-\d{2,9})|(ABz?-\d{3})$"


Ideally it should not allow parameters with ++ or -- at the end, but it does. Why is the regex not working in this case but works in all other scenarios?

ABC-12 is a valid.
ABC-123456789 is a valid.
AB-123 is a valid.
ABz-123 is a valid.

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