As Jeff has said, there has been endless speculation as to the function of the bifurcation on a "baidarka". At this point, no body knows why the design evolved to its current form. The only thing anyone can do is guess. "Form & Function of the Baidarka" by Dyson is best compendium of these speculations (link below). These ideas were discussed ad-nauseam on the Baidarka Mailing List http://robroy.dyndns.info/baidarka/.

From a on-the-water performance standpoint one thing is obvious. The form of a bow only effects the performance to the extent that the bifurcation is in the water. Other than windage effects the bow shape can not impact how the boat performs until it gets wet.

With many baidarka forms the bifurcation is well out of the water. In fact often the front 18" to 24" of the bow may overhang on flat water. The obvious conclusion is the bifurcation has absolutely no performance function in flat water. Note that there are some reports of baidarkas being paddles with stones for ballast ( https://books.google.com/books?id=oGFHP-79tnQC&pg=PA31&lpg=PA31&dq=baidarka+ballast+stones&source=bl&ots=2PLtJtsZdk&sig=B6hJscje1HjvcMinT4ePX8W_zH8&hl=en&sa=X&ved=0CB8Q6AEwAGoVChMI-u3SpKLYxgIVy24-Ch0cOgzD#v=onepage&q=baidarka%20ballast%20stones&f=false ) 50 pounds of added weight will change the waterline so maybe we are just using them wrong.

In waves, the bow overhang will start to come into play. In much the same way the flared bow sections of the Greenland-style overhang provides incrementally more reserve buoyancy as the bow penetrates deeper into a steep wave, the baidarka bow is relatively fine near the keel and wider higher up. As a result the bow can provide significant lift for climbing over waves. On some bidarkas, the bifurcation does help create a finer cutwater followed by a quickly increasing volume when the upper bifurcation kicks, but this is not the case for all baidarka forms. In some both bifurcations are narrow and low volume.

It should be noted that for most baidarka forms, the middle section of the kayak was quite different from Greenland style kayaks. Even if the bow and stern forms of the baidarka were modified to match a Greenland style kayak, the baidarka would still perform quite differently from Greenland style kayaks. The hull is rounder, with softer chines with a bit more deadrise at the keel. The plan view in some cases showed more gradual waterline curves with less pinching in the ends than Greenland style designs. Baidarkas are typically higher volume with little flare above the waterline. It would be a mistake to attribute all performance differences between Baidarkas and Greenland style kayaks to the end forms. There is a lot more going on in the designs than just what is going on at the ends.

It should also be noted that within the "baidarka" designation there is a large degree of variability. The baidarkas of Kodiak Island were quite different than those of Unalaska, and Nunivak Island bidarkas are different yet.

The original reason for the bifurcated bow is lost to time, but we can use the ideas seen in traditional designs to develop our own new ideas and uses. If you like the design and it works well for the use you put it to, then it is a good design for your needs. If the design performs a function that is beneficial for your enjoyment of the kayak, then that is a worthy function for the design element whether or not the orginal Aleut builders were thinking along the same lines.