Hi
Thank You for the response.
I have a few more details that i probably should have included in my original post. Michel Robineau dit Desmoulins was married in Montreal in 1710.The records i have say he was baptized at the St. Roch Parish in Paris around 1683. His mariage record specifically says his father's name was Simon Robineau. He would have arrived in Nouvelle France in the early 1700's but have found no trace of his arrival yet. After his mariage in Canada in 1710 he had several children and as you indicated some did keep the Robineau name and others kept the Desmoulins name.
According to records at Archives Canada "Dit names" were quite common in Nouvelle France in the early days of the colony. I do have several theories as to where the "dit Desmoulins" name comes from one of which involves a hill that was called "coline Des Moulins". This hill was in central Paris (adjacent to St. Roch church) and was apparently "removed" in the 1650's. This makes for an interesting theory.

I have a few more theories on my blog at
www.robineau.ca. The 'Dit " names were more common in Nouvelle France until the mid-1800's when the practice of using "dit" names seemed to almost disappear. Their are also theories about why this happened as well.
My brick wall at the moment are Michel's parents who were Simon Robineau and Anne Robineau (Larche). They would have been living somewhere around the St. Roch church in central Paris in the late 1600's. I am hoping that a Robineau in France eventually does their tree and they come up to the same ancestor. That would be exciting.
I look forward to any further comments you may have.
Merci
Roger Robineau