Yes it is a lamination. Very common on the War Nickles. They seem to have had a problem in getting the right mix of metal... Speedy
I had a few with similar lamination errors. I'm guessing they were more worried about just pumping them out rather than producing them well, what with the war and all...
The manganese just didn't alloy well with the silver It's also responsible for the "greasy" appearance of the worn pieces.