They're not fake zdenal, diesel has two brand presences in the uk and Ireland which came from a split in the brand in the 80s. Diesels uk division went out on it's own and kept the name and now trade independently. It's a cheaper, more generic version of the brand with a completely different ethos to Italian diesel but definitely not fake.
As for coolaboola(love the name, love/hate right?) it's gonna be really hard to find a pair of those as they don't have the following that Italian diesel has and if they've been discontinued, which I assume they have, then I'd say it'll be impossible to find a pair now.