I think you misunderstood (or I misformulated): I'm not accusing Norway of selling more certificates than they should, I'm saying that the buyers of the actual "green electrons" won't feel the tiniest bit dirtier from the certificates having been sold. The "double spend" would be virtually clean (from a certificate) plus actually clean (but with the certificate sold).
It boils down to the question wether this is true or not:
> but they did have to at least leave Norway in a way that the Norwegians can't count them in their own consumption
This reads as if Norway could only sell certificates for surplus energy they exported (sans certificate), but I think they can sell certificates for as much green energy as they produce, virtually downgrading their own consumption to coal/gas/whatever energy source is greenified with the certificates. Of course it would hurt their on-paper emissions, but who would honestly care about those when you know that in reality you are clean?
I'd certainly love to be proven wrong on this!