You aren't going to get that from a breeder. They aren't going to risk being kicked out of their national breed club etc just because someone on the internet wants verification. People don't play games with this and don't hesitate to call someone up in front of an ethics committee.
Best look towards science and breeding laboratories to get a colony of merle dogs to start breeding.
Honestly there may be a way to breed these double Merle safely but a greater question is why and if so why does it have such a bad name? I can't justify dead puppies, culling, and what not just to get an ideally colored dog. I suppose it confuses me more than anything.
The important one I saw earlier was if a Merle to Merle was *not* dangerous why is the owner/breeder being very clear they won't breed Casper to another Merle?
The important one I saw earlier was if a Merle to Merle was *not* dangerous why is the owner/breeder being very clear they won't breed Casper to another Merle?