Hi John
I had the same thoughts about you on Pierre. A marriage at 15 was virtually unheard of amongst the Huguenots. Generally boys did not become adult members of the congregation until 18-21, and girls around 16-19. On occasion they were slightly younger or older but rarely by a very great deal. Even then it was frequently a good 4-5 years after that they would marry, as a community they rarely rushed into it, and were very much opposed to child marriage.
A Pierre Bettembo was accepted as an adult member of the Huguenot congregation at Threadneedle Street on 27 June 1739 on the testimony of his aunt, age noted as 17. It would be likely this is the Pierre born 1721, and certainly he would not have been married before that point as he would have been considered still a child within the community. I think it was actually likely he was the same Pierre who married Anne Brisset/Breeset on 09 Jul 1746 Saint Dunstan,Stepney, and had several children with her baptised at Threadneedle Street French Huguenot. 25 was a very typical sort of age for a Huguenot male to marry.
That said I still think it is possible Pierre who married Marie Catherine Dujardin may have been from the same parents.
They had an older Pierre baptised at St Jean, Spitalfields on 28 Sep 1712. I cannot find a burial for him in the East London churches (Huguenot chapels were not able to bury their own dead, so would have used the nearest local Anglican yard). The practise of naming children with identical names is more common in the French community than the English. In English families it rarely occurs unless the first child has died, but in my own Huguenot families alone, my 'Mourgue' family named three sons Etienne, two of which both survived to adulthood, and My 'Picard' family, incredibly named 7 sons Isaac, and 4 daughter Elizabeth, and at least five of the sons and two of daughters reached adulthood!
It seems confusing, but I imagine within the family they must have been known by individual 'nicknames', or I can't see how it would have worked. It was traditional for Huguenot children to take the name of their godparent, Pierre Bettembo 1712 was named for his godfather Pierre Ferrettes, and Pierre Bettembo 1721 was named for his godfather Pierre Ferri. If both these men were important to the family, and they wanted to honour them by making them a godparent to a child, the fact there was already a Pierre in the family may have been secondary! This was also the case in my family the Mourgues, the repititon of the name being explained by the parents choice of godparent.
Of course this is speculation but I cannot see any other obvious candidate, and the other facts seem to suggest such scenario.
John if you are visiting the Huguenot Library would it be possible to ask you for a look up on my behalf. Unfortunately I am unwell at the moment, in an out of hospital for various procedures, so not really able to go myself for the foreseeable future. Of course if you are too busy with your own work, I quite understand, please just say, not a problem at all.
Regards
Richards