The typical Dornier ‘Flossenstummel’ (sponsons, aerofoil-floats) first appeared in 1918 with the Dornier Rs IV.
Seven Dornier A Libelle I (Dragon Fly) were built and seven slightly bigger Dornier A Libelle II.
Here is a photo to show the sponsons
http://www.seawings.co.uk/images/DoLibelleWR%20ex%20Knut%20Erik%20Hagen%20of%20Norway/2.JPG