At first glance, it appears to be a double-clipped planchet. If so, it's a real keeper and may have some value. Stay tuned for a member more experienced with these types of errors, to "chip" in with a more definitive answer. Thanks for posting such an incisive question, and most of all, Welcome to Coin Talk !!
I'm not convinced it's an error. It looks like pmd post mint damage. There is upset rim behind the clips. I dont think this is possible. On genuine clipped planchets there is no rim on the clipped area.
when I first saw this I didn't respond because I thought it look like someone made a spacer out of it a long time ago, thus two flat, parallel(ish) sides. But I'm definitely no expert on clipped planchets especially flat clips.
^^^^^Thus, the statement : Stay tuned for a member more experienced with these types of errors, to "chip" in with a more definitive answer.
Can't say for certain from the edge pics, but the edges look smooth and do not show the punch/tear characteristics of a true clip. I'm leaning towards damage after it left the mint. Clearer pics of the clipped edge would help.
Could it be that because it is such a small clip, that is why it looks the way it does, along with the wear that comes with a hundred years of circulation? I know that if I had come across this, or a similar coin, I would have been rubbing my fingers along those slight curves even as I looked at them. I don't know. What is the consensus?
On clips I have seen, there is either evidence of the Blakesley effect, which would not be evident for this coin since it is at 180 degrees from the clip, and/or a slanting of devices at the clip down into the area of the clip. I don't see this second thing. Wonder what @Fred Weinberg would say...
Perhaps these clips are so close to the rim that they don't show the normal things most clips show? Perhaps they only show the interior of the rim, so close to the edge that it only looks like more rim? This is suppositions and conjecture.
Post mint damage. the edge does not form like that on a clipped planchet. Do not forget what the upset mill does/does not do to a clipped planchet.