[Advaita-l] Two Sankara-bhashyas on Kena Upanishad

[Sunil Bhattacharjya]

Adi Sankaracharya wrote Padabhashya for all the  major upanishads including Kena but for Kena he wrote an additional Vakyabhashya.
 
If the Vakyabhashya of Adi Sankaracharya was based on the one such written earlier by Brahmanadin, then the question arises as to the possibility of some disagreement of Adi Sankaracharya's views with those of the views expressed in that lost work of Brahmanandin on  Kena and also that his own earlier Padabhashya on Kena could not alone stand in front of the Vakyabhashya of Brahmanandin.. Whether he wrote the Vakyabhashya to  challenge  the views of Brahmanadin or wrote it without referring to the Vakyabhashya of Brahmanandin there must have been some justifiable reason for Adi Sankarcharya, such as the need to convey some additional messages through another Vakyabhashya on top of what he conveyed  through his Pada bhashya on Kena. Secondly it can also be that much after penning the Padabhashya Adi Sankaracharya realized some additional features of Kena, which made him feel the necessity of writng a Vakyabhashya on that.
 
Either way, ie.whatever the case might have been out of the above two possibilities,  has anybody done any comaparative study of the two bhashyas on Kena?
 
Regards,
 
Sunil K. Bhattacharjya