Les Editions de la Porte Dorée
"Les Editions de la Porte Dorée" is a French publisher, specialized in editing works (mainly novels), on individual request of people seeking to be self-published at "author's account" - that is to say outside of any traditional publishing houses.
As far as "Mandrake the Magician" is concerned, it seems that one collector asked some reprints of Sunday Pages, translated in French.
In September 2015, at least two books of 60 pages each have been edited in such a way but in a very few copies (each of them in 12 numbered copies only). However a total of 10 published issues is mentioned on the back cover of those issues, with a mention of other future issues, but it remains uncertain that they really exist.