Exception to Unique Field

Pretty straightforward question: I have a text field that requires a unique value. However, sometimes when a user is adding a record, they don't yet know the correct value to put in for that field, and it gets confusing when they have to go back and update the field to the correct value, which sometimes gets forgotten. Is it possible, maybe through data validation rules or something else, to create kind of a dummy value, an exception that is allowed to be non-unique. So, if users don't know the correct value when adding a record, they can always put 000000 or 123456 or something along those lines, that can then be updated later, which would put all of the records with a value that we know needs to be updated in 1 report.

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Harrison Smith
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