Yes. This contract would have been with family records. I found my ancestor, Jules Simon Bourgeois' contract with family papers in Austin. The contract was signed by Bourgeois on July 17, 1843 in Castro's apartment in Paris. It was witnessed by his protege, Auguste Fretelliere. Apparently the colonists kept the contract with them and it was as important as their passport. Bourgeois' contract was amended with the information from Castro when Castro told the first group of men that he would give them additonal land for being to go with the Sept. 1 group.
I have never seen another contract in my expedition to different Archives. However, I did not look for the records for every colonists.
FYI -- the Colonists were given a certificate in Castroville that they used to register their land with the General Land Office. Your Batot certificate and survey records are at: http://wwwdb.glo.state.tx.us/central/LandGrants/LandGrantsWo...
Hope this helps.