If '[<Tableau sprite(in 1 groups)>]' is the result of printing colliding_with, I'm pretty sure that is a list of only one instance of a Sprite. If it were the Sprite class itself if would be represented by '<class 'pygame.sprite.Sprite>' or something like that, and would not contain the number of groups the sprite is in.
The sprites all have unique names... but spritecollide only returns
the class of the object, not the name or any other identifier to
distinguish between objects of the same class...