Starship Asterisk*

JohnD wrote:"Double ring craters are common features on Mercury."
And often see elsewhere

That's "common". Means there are lots of them, that they are not rare.

Not only that, but double ringed craters are far from mysterious. As the APOD notes, they are not completely understood, but that doesn't mean they aren't understood at all. There are reasonable models and simulations that go a fair way towards explaining them, and which also partly explain the observed differences in ratios between single and double ringed craters on Mercury, Venus, Earth, the Moon, and Mars (all of which have double ringed craters).

It is likely almost beyond doubt that double ringed craters are the product of certain crater forming processes, and don't involve multiple impacts.