Edit: Never mind. I looked at your picture. It appears that the Serial Monitor is adding a carriage return to the string entered. Change that to nothing appended to the string to get rid of the duplicate response.
That was it !! Shame on me, I could have find it by myself with a little care :-((
Thank you very much for pointing it !
But what do you mean by "my comment is wrong ?"
EDIT : never mind, I found it ( heedless again 
); the num range is 1 -100 INCLUDED, not 0-100 ....
Thanks again !