Hello kellbuck -
It sounds like you may have changed the Template Title field on a listing to be different than the Title field and then used create similar on the listing.
If the Template Title field is altered from exactly matching the Title field of a listing and then Create Similar is used, the sync between the two fields is broken, so updating the Title on the newly created from similar listing will not update the Template Title field as it would on a listing created from scratch.
So, you would need to update the Template Title field on listings you create from similar where the base listing does not have exactly matching data in these fields. Note: if you later update these fields to exactly match and then save the listing the sync is re-established between these fields.
If you have run into a different circumstance or are encountering a different behavior in this circumstance, please feel free to file a support case with the details of what you've run into and please include a few sample saved listings titles where this has occurred and we'll be happy to take a further look.