AVP 16.102.1 might have been the 'master' mantra and the later versions modelled on it.
Best
DB

--- On Sat, 2/4/11, George Thompson <gthomgt@GMAIL.COM> wrote:

From: George Thompson <gthomgt@GMAIL.COM>
Subject: Re: [INDOLOGY] Antiquity of the mantra: pūrṇam ad aḥ pū rṇam idam ...
To: INDOLOGY@liverpool.ac.uk
Date: Saturday, 2 April, 2011, 10:06 PM

Hello Madhav,
 
There is also a variant at AVZ 10.8.29 that may be if interest.
 
George

2011/4/2 Deshpande, Madhav <mmdesh@umich.edu>
Dear Colleagues,

    The very popularly recited mantra "pūrṇam adaḥ pūrṇam idam.." occurs as the beginning Śāntimantra for the Īśāvāsya-Upaniṣad.  It came to me as a surprise that Bloomfield's Vedic concordance does not list this among the mantras, nor does Jacob's Concordance of the Upanishads list it.  I was equally surprised that most published editions of the Īśāvāsya-Upaniṣad do not begin with this mantra, but, as expected, they begin with the mantra: īśā vāsyam idam ...   Among the editions I have consulted, only the Ānandāśrama (Pune) edition of the Īśāvāsya-Upaniṣad with Śāṃkarabhāṣya offers this mantra before the text of the Upaniṣad proper, but Śaṃkara does not comment on it, nor does any other commentary that I have seen comment on it.  I am wondering if anyone has seen any research relating to the antiquity of this mantra.  I would be most happy to receive any information on this subject.  Best,

Madhav

Madhav M. Deshpande
Professor of Sanskrit and Linguistics
University of Michigan
Ann Arbor, Michigan, USA