Adding some new information to help searches a bit more on the shield cents:
I notice some are still having a little bit of problem with doubled dies, so I thought of something the other day that might help. When you look at the enclosed devices on letters/digits, have you noticed how the centers of these devices are affected? The show distortion more often than just looking at the devices. So I thought I would give show some examples to show you what I mean. When you look at these areas, you may think differently with this information?
On dates the devices that are doubled on the single squeeze dies reminds me of over inflated devices. The distort in shape and look wider, taller and every thing else that can happen to them:

The first image and the third images are normal dates to compare with the images.



LIBERTY:
On LIBERTY check the insides of 'B, E, R and the TY is often showing doubling. Sometimes it is at the top, other times at the bottoms. On the 'Y' you can see the top forks of that area showing wider branches on one or both on this device.



The key is to note the distortion making the devices larger. Stop looking at the sides of the devices, the spread will be noticed in the centers of the devices.
Motto:

These will occur a lot less on the motto areas for doubled dies. But a few examples are pictured. I noticed on the UST area sometimes shows dimples on the fields where the die snapped into the proper alignment.

Hope this helps with your searches.