No need to guess. They are nonces that have generated more than a single solved block.
If I am not completely mistaken, the probability of having such nonces given the current length of the blockchain and the breadth of SHA-256 is...for all
realistic purposes zero. Well, not really. I forgot the target. And the difficulty adjustment over time. And that there was a very low difficulty at the beginning.
It would be interesting to know the probability of such a thing to happen. I assume this happened in very early blocks? Anyone having the block numbers at hand? (My own block explorer version does not yet support searching on nonces)