Bottin with one or two T  ?

Thanks to several etchings from Leonide Bourges, we know Pierre Edouard Frère and his son were friends with Charles Daubigny. Their names are engraved on two of the etchings. On one of these, we see Pierre Edouard Frère and his son seated on the famous boat, belonging to the Auvers-sur-Oise painter, named Bottin.
On the boat, Daubigny was painting along the Oise and Seine river. The original name of the boat had only one « t », déformation of the flamish word « botkin » meaning little box. It was a nickname shot by a sailor, from his barge, disturbed by the little boat.
Later, in 1868, Daubigny built larger boat, named « Bottin » with two « t ». His son Karl, painter as well, was riding very often with him. We can see Karl shown next to Pierre Edouard Frère on one of the Leonide Bourges etching. Incidentally, they both died on the same day.