The **correct way** to say 1 000 001 in French is indeed "*un million un*". I do hear sometimes "*un million un*" for 1 100 000. 
It may come from "*1.1 millions*".
It is **incorrect** and as we say in French it is "*un abus de langage*". 


1 000 000 : "*millionième*",
1 000 001 : "*million-et-unième*"