Most of Thurner's scores appear to have been published under the name Théodore Thurner aîné (or ainé). A comparison of the work list found in Fetis confirms that Théodore Thurner aîné (or ainé) is Théodore Thurner (1833–1907). At least one work listed below (Mazurka de salon, Op.5) was published under the name Théodore Thurner jeune. It is not known if this was Théodore Thurner aîné's younger brother or son. -- Conceivably (unlikely?) the same person, if (admittedly confusingly) this was a vertical relationship while aîné was a horizontal one- but yes, your interpretation seems more likely. (One possibility is that modern descendents if any of the Thurner family might have some family records that can clear things up. ... hrm.)
