I think I have an answer for this proof frost doubling 1964 1c.

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The only possible rationale is the mint mistakenly used a retired die, dipped it in the acid for the frosting, and then polished the highest points away...

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During that double hubbing we see the need for the new by what the old shows. The split top IN-N is a very present image in the early 60's. This is a...

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This image has separation (green) when they were laying the bow tie top over the diamond.
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The blue arrows show a tie image portion which covers the bottom of Lincolns bow tie. So the mint said they intentionally covered the bow tie bottom with...

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I was just doing some math on 1964 cent proof coins. The implied rarity of strongly frosted coins.
If frosting lasted 100 strikes and each die...

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Beautiful squeeze.
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I've been trying since 2014 for my first listing. I knew this would be that one. I was just waiting for Wexler Doubled Dies to open for submissions again....