Has there ever been two federal reserve notes with the identical serial numbers in the public or private sector?

Counterfeits for sure may all have the same number.

How can I tell if a 1934A frn is real or counterfeit on my own without mailing it out or leaving it with someone?

It is likely real.
Have to go to work, was hoping you would say you have 2 or something, do you think someone else has one?
Ran out of time.
Having 1 may not say much, do you have a stack of them?

It is likely real.
Have to go to work, was hoping you would say you have 2 or something, do you think someone else has one?
Ran out of time.
Having 1 may not say much, do you have a stack of them?

I have one and can locate the other

I have one and can locate the other

Its likely real from what I can gather. The other is already certified