Update - from Planet Four Talk
Science team member Meg Schwamb said that these craters reminded her of the snowman,
a double crater on Vesta, and linked to a blog
by Emily Lakdawalla who considers how the snowman mighty have formed.
The lab experiment image in the first post:
is from the LROC article on one of the lunar double crater examples I gave (Tres Amicis
) and I take this to imply that there are more lunar examples. The article highlights the septum between the craters rather than the more distinctive ejecta but if this is how the craters form then there should be doubles with this ejecta pattern on the Moon.