Double ended bars
Welcome to the forum, this thread has risen a few time on the forum before, here are my findings on a double ender V's single ender.
I have made and used a double ended outfit before, 2 X Dolmar 9100's, 95cc, a piece, very good bucking and milling saw, they have the same bar fitting as the big Stihl 880, and you can buy both for about the same price as the big Husky or Stihl.
I found that there is no big advantage in having two saws, unless you are cutting 60 inches or wider all the time, cutting smaller lumber below 24 inches is a real waste of fuel and oil, You can turn off one engine and let the one do the work on a smaller log, but that is plain silly, having a second saw as a roller nose to guide the chain.
You would be better off buying one big saw, my choice only of course, A big Stihl Magmum 880 and a 50 inch Cannon or similar quality bar, change the tip and use a 9 tooth sprocket to drive a 325 chain, this save heaps of power loss and cuts much quicker, 440 is a big waste in timber especially timber like walnut and oak, 325 gives a better finish, more cutters, better finish.
Two saws also need to be perfectly balanced for revs or one will simply soak up the power of the other one, this is not at all easy to do, unless you have an electronic tacho to constantly check things, you cannot guess this stage at all, it must be right.
If you look on the Procut website,
http://www.procutportablesawmills.com/doublesawbars.htm you will find more and the same information on double enders.