___________________NZ31200_________NZ3120A___________
1   ^N.*?[^0][^0]$     NO match        NO match
2   ^N.*?00$           match           NO match
3   ^N.*(?<!00)$       NO match        match
4   ^N(?!.*00$).*$     NO match        match
5   N.* and !/00$      won't do, as it must be ONE RegEx
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