Appears to be machine doubling, but the notching on LIBERTY makes it confusing. But on the big one for that year doesn' have the notching on the tops of the devices of LIBERTY.http://www.coppercoins.com/lincoln/...ie_state=mds
But more is involved on a doubled die. The devices on the link above enlarge the devices. I don't see that on your images.
The reason so many are found together is probably they came from a roll/rolls that were OBW rolls. If they are machine doubled, the doubling should be different from coin to coin in the slightest. If they are a doubled die, then they should all be exactly the same. Here is an example:
When looking at these images, they are all different but are from the same die as you can see a common marker on each coin. (NW/SE die scratch)
So if you could compare the examples to each other and see if all have the same exact notching on LIBERTY that might help with that information. There are cases where a coin can be machine doubled and a doubled die. But I would like for this information first and see if they reveal something about the batch of coins.
Richard S. Cooper
Some have asked about my images I use and I've glad to say I've completed a DVD of these. Ask if you are interested.