A short time ago, I posted pics of one 16 D/D (Breen 4223)that I found:

Here is the second variety. Breen (4224) calls this a Large D over a small D.
To me, this is neater than the first:

Searching through heritage archives, I cannot find 4224, but I can find 4223. I have talked to a few people and they said 4223 is fairly common. Anyone know about 4224?