It looks like a relay race. The "6" passed the baton off to the "9" and the "9" passed it off to the "1". Chris
What, exactly, are you talking about? The little "box-looking" thing? If so, I'm not exactly sure what the reason or cause is, but if memory serves me, it's not an uncommon thing on small dates. Perhaps @desertgem is familiar? I do believe he's written of a fondness for this date/mint in the past.
With the understanding that you qualified the statement with "to me", the problem with that theory is that said anomaly appears on both Philly and Denver SD cents of this date (I forget if on PRs as well). While I suppose it's not outside the realm of possibility that the design could cause similar issues upon striking, another cause seems much more likely, perhaps something with the master?
Here's some images from Wexler site on the small date . The first image shows strong extra thickest on the date .
If your images were Ricks then you would have something. But you DON’T have Rick’s coin and your coin is like I stated before: A NORMAL COIN! Do yourself a favor and pass these non error coins up and keep looking for others. When you find one it will be obvious, if it’s not and you got to squint just right in the right light then it’s NOT AN ERROR. I wouldn’t say this if I didn’t JUST look at Lincolns only, ever, for the last 40 years. Take a look at my Avatar. These are 7500 Lincoln cents that I looked through in Sept-Oct2017 alone. All bank rerolls. I collect 1930 to 1982. I kinda see a few. I just hate to see you waste your time on such minor non errors when there is a whole world of real collecting to be focused on.
That it displays an anomaly known to exist on examples produced at two mints, so with all due respect to Paddy, the chances of said "box-looking" thing being die chips or due to a worn die is likely slim to none. My guess is the cause has something to do with the master, meaning like the 72 master doubled cents, it's nothing special. If you compare to other SD coins from both mints, you'll see what I mean. Even Rick's example shows it. That said, do be careful about being pulled along on any wild goose chases.
Okay if you can call it from grainy images. The OP needs to have some good ones for all else to see so we aren't looking at pixelized shadows or it’s just a waste of our time. I'm personally not ever going to make any kind of value judgment off of grainy, incomplete, out of focus images and I think it’s unwise to expect us to do the same.
