Another 1970 Proof Set Question

Now that I'm on the other side of the country that I should be on, I do have time to go through all the coins that I left here. Since I'm still new to this, but trying to catch up as fast as possible, I'm gonna have a lot of new questions. Here's the first one....
My uncle left me 2 1970 proof sets. He has marked on them Large Date over Small Date, and unlike the other dd/md set posted earlier, there is no prominent doubling, but what is different about them is that parts of the date are fat, and taper down to the size that they should be. Take the "7" for instance, the diagonal is fat at the bottom, and the horizontal line is a nice clean line. What caused this? Is this a variety? Is it worth anything, or is it nothing at all. I would post a picture of it, but I can't reach my camera, so if you would give some input I would appreciate it.
-David
My uncle left me 2 1970 proof sets. He has marked on them Large Date over Small Date, and unlike the other dd/md set posted earlier, there is no prominent doubling, but what is different about them is that parts of the date are fat, and taper down to the size that they should be. Take the "7" for instance, the diagonal is fat at the bottom, and the horizontal line is a nice clean line. What caused this? Is this a variety? Is it worth anything, or is it nothing at all. I would post a picture of it, but I can't reach my camera, so if you would give some input I would appreciate it.
-David
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Comments
During the time, creating a die entailed two or more "hubbings." Most of the time all hubs had the same design; however, there are two types for the 1970 cent. Apparently, the operator inadvertently picked up a large date hub to complete the job started with a small date hub.
Here is their description: "Extreme extra thickness is evident on all letters and numerals, with some separation evident on the lower portions of the digits. "
Hope this is of some help.
Thanks again,
-David