From: Rabbi Moshe Sofer
To: Rabbi Yaakov Koppel
A man known as 'Anshil' gave his wife a get using that name, but a prior document surfaced where he signed as 'Antshil' with an extra tes. The Chasam Sofer rules the get is fully valid on multiple independent grounds: the variant is merely a dialectal pronunciation of the local Slovaks and not a separate name, the consistent usage at both the place of writing and delivery was 'Anshil' only, and even under the strictest views the takanas Rabban Gamliel does not apply to a name unknown at the time of writing.
Source: Shu"t Chasam Sofer EH II §24