1944 S Lincoln Cent Double Date

In going through some coins from my dad's collection to incorporate with my own, I came across a Lincoln Cent that he had labeled as a Double Date. I have looked for references to other 1944-S Double Dates, but have not found any. I have attached an image that I hope clearly shows the double date.

Any information on this would be appreciated.

If the die has worn out by use, they are 'recut'
That gives the effect you see

That appears to be "machine doubling:"

http://www.lincolncentresource.com/FAQ/machinedoubling.html

Thank you for your help.