Durande and Déruchette are the same name. Déruchette is the diminutive.
This diminutive is very common in France.
In the country the names of saints are endowed with all these diminutives as well as all their augmentatives. One might suppose there were several persons when there is, in fact, only one. This system of patrons and patronesses under different names is by no means rare. Lise, Lisette, Lisa, Elisa, Isabelle, Lisbeth, Betsy, all these are simply Elizabeth. It is probable that Mahout, Maclou, Malo, and Magloire are the same saint: this, however, we do not vouch for.
Saint Durande is a saint of l’Angoumois, and of the Charente; whether she is an orthodox member of the calendar is a question for the Bollandists: orthodox or not, she has been made the patron saint of numerous chapels.
It was while Lethierry was a young sailor at Rochefort that he had made the acquaintance of this saint, probably in the person of some pretty Charantaise, perhaps in that of the grisette with the white nails. The saint had remained sufficiently in his memory for him to give the name to the two things which he loved most—Durande to the steamboat, Déruchette to the girl.
Of one he was the father, of the other the uncle.
Déruchette was the daughter of a brother who had died: she was an orphan child: he had adopted her, and had taken the place both of father and mother.
Déruchette was not only his niece, she was his godchild; he had held her in his arms at the baptismal font; it was he who had chosen her patron saint, Durande, and her Christian name, Déruchette.
Déruchette, as we have said, was born at St. Peter’s Port. Her name was inscribed at its date on the register of the parish.
As long as the niece was a child, and the uncle poor, nobody took heed of her appellation of Déruchette; but when the little girl became a miss, and the sailor a gentleman, the name of Déruchette shocked the feelings of Guernsey society. The uncouthness of the sound astonished every one. Folks asked Mess Lethierry “why Déruchette?” He answered, “It is a very good name in its way.” Several attempts were made to get him to obtain a change in the baptismal name, but he would be no party to them. One day, a fine lady of the upper circle of society in St. Sampson, the wife of a rich retired ironfounder, said to Mess Lethierry, “In future, I shall call your daughter Nancy.”