Actually the Germans are not allowed to short, but they do anyway, but they do not go through Canadians, they go through US Corresponding clearing firms like Bank of NY for stock loan, then they run the trade through some obscure B/D. You can see this a mile away. They try to tap you away, and eventually you just pull your bids.
Bear and BBH were bad at this. And when I was getting tapped all day, and figured out who me contra clearing the next day, I stopped playing the game.