Ewesheep: bi-blue is simply an all-black dog with the merle gene thrown in. In most collie-type breeds' cases, there is also the Irish white color pattern bringing in that third color, but they still refer to it as bi-merle. These colors and more were present in the original collie stock, but have been bred against in certain modern breeds according to the breed clubs' tastes. The variety is still found in border collies, Aussies, and shelties though I suspect the Aussies will lose many of the "off" colors as they become more standardized. They'll still pop up on occasion, though, especially the recessive colors! Those still pop up in rough collies, in whom they've been bred against for over 100 years now. Usually when they do, the first thing squawked is "mongrels!" due to a lack of understanding of color genetics. It's certainly possible that the dogs in question aren't purebred, but it's not a given just because an odd recessive has been stumbled upon. I've seen recessive bi-black and bi-merle collies, liver with tan point collies in both solid and merle, even a sable whose black points were liver! And other fun stuff like harlequin merle. If you'd like, I can post pictures over the weekend. I was initiated into my coat color genetic geekery by my dog Maynard, who appears to be a dilute blue merle. You can visit him on the link in my siggy.
ChickenFanaticAB: it's difficult to tell from those photos, but I would guess either a sable merle or a brindle. Or both? Now that would be a crazy combination! Both genes are dominant, though, so I don't see why it couldn't happen.