Madeline by Ludwig Bemelmans. Why 12 girls in their table?

Question

After the visit of Madeline in a hospital by 11 little girls, they had dinner with 12 girls...

Is this a mistake?

But when they brush their teeth, there were only 11 girls.

Answer 1

Looks like Miss Clavel got another girl!  Yep, Madeline is in the hospital, 11 girls should be there, there are 12 sad little girls at the table, then 11 brushing their teeth, and in bed.

Good eye!  Looks like an illustration oversight to me.  Oops!

Answer 2

11 girls and Madeleine