It's up to the team and customers to decide on that however. Database integrity is particularly important, so with limited information, I'd say you made the right decision. Therefore the first draft of the code was not good enough.
So, we should all be in agreement now, right?
> It's up to the team and customers to decide on that however.
You said yourself:
>the consequences of a dupe would lead to a pretty bad customer experience.
I've seen many situation were a duplicate wouldn't matter to a customer. It would matter to me because like you, I'm a perfectionist, but at the end of the day, it's both the team and customers that decide together.