Found A 1975 Broken Cracked Proof Set From My Grandpa's Hoarder Drawer 8 Years Ago After His Passing

I've been sitting on this for years since my grandfather passed away. I found this cracked and broken 1975 proof mint set in his drawer of collectibles. It's been with me the past 8 plus years falling in and out of the broken case until I recently got into coin collecting and decided to move it to a more secure case just for the time being.

I do understand there's only 2 known of the 1975 no S proof dime and the likelyhood of a 3rd is near impossible. Especially with this one coming from a broken set. So I've just kept it with me for so long and thought it was just the kind of thing my grandpa would do when he hoards things is that he'd forget where he organized it and rearranges things all the time. But it's always looked a bit different than other 1975 Philly dimes under natural lighting in the day time. It only shows its orange ish tone under natural lighting and the relief and strike looks higher than that of the Philly coins. On don't know if the fields have been cleaned or post mint polished but it does look like a mirrored field except the original luster/mirror shine of a proof polished is faint or faded?

This might be a stretch. I might be going off the deep end. BUT THE proof 66 example that was stored away from an Ohio collector has never resurfaced for the past 40 plus years. Nor has anyone ever been able to confirm contact with that collector. Finding a new 3rd example is a reach. But am I even more crazy to think that I have the proof 66 2nd example in my possession somehow?

There is a definite certain for marker confirmed by Coin World about the proof 66 example is that it has a stroke through on the reveres.

"examined in 1977. The dime has a visible, unique marker not seen in the photographs of the other example. The Ohio coin was struck through a thread or hair on the reverse that left a shallow depression in the coin extending from the field to the right of the top of the torch into the bottom of the flames".

I need help. I think I'm going crazy. Please just confirm that I insane so I can give this a break and not let it ruin my personal time enjoying the hobby.