What you are describing here is easy enough for an arborist, but a little bit trickier for someone who is not trained to fell trees.
If the trunk of the tree is split into 2 12" DBH trunks there are enormous stresses in the tree. Simply notching and felling the tree won't do. If you do that the tree could easily kick back as the stresses are being released and strike you dead.
To drop the tree safely you're going to need to top it and remove it in sections from the top down.
This is going to require climbing gear and a helper to belay you.
You'll want to remove the tree in roughly six foot sections. You'll need to rig the piece being removed onto a belay device so a second person on the ground can control it.
You'll want to remove from both splits of the tree evenly. If you completely cut one side you'll overload the root system and the tree could fall, with you tied to it.
Once you have the tree topped to within 8 feet of the ground then you can cut at the split.
Like I said, this is a $3,000 to $4,000 job due to the requirement of a crew and specialized climbing gear.
Depending on species a tree with a 12" DBH could be over 75 feet tall.
More information and pictures would help w/ an accurate bid.
For example if the tree is rotted out or diseased it's too weak to safely climb/belay. This would necessitate a manlift and a crane.
OK, I'll admit it..... I'm just a dumb electrician. But I'm cutting down a tree for a good friend only because things are slow and I have a chainsaw.
I'm at a loss as to what to charge.
Tree is two minor trunks about 12" diameter each, which had split off from the rest of the tree and were leaning at a 30° angle on another tree. All this person wants is to bring it on down so it doesn't fall on someone, cut it up and place it all by the alley for anyone who wants firewood.
No overhead utilities or structures to worry about. Just curious as to what a fair price would be.