Yes, they are the same knife. It's very common in Japan for knives (and other products) to be made under contract for a specific seller. Sakai Takayuki, Yoshihiro, and Aritsugu are examples of shops (or entities that were probably once ships) that sell a number of unique products under their own name that you can find nowhere else. This is less common in the western markets at that fact is something CKTG has taken advantage of since no one seems to really know what's going on here.

You see, instead of working with Tojiro to sell some exclusive product, CKTG has gone ahead and purchased a number of existing products and replaced the original maker's mark with something he invented himself. I suspect he is then selling the CKTG-marked Tojiro knives at a loss to try and drive away competition. Again this is just a suspicion, but if true these are very anti-competitive practices and you should think carefully before buying the discounted knife.