New to group

Hello Group!

I have been lurking for a while trying to get a feel for the group,
and have just worked up my courage to ask a question.

I adopted a 2-year-old male tabby (Bozo)six months ago to keep
my other cat a 3-year-old female calico (Kissy) company. Both
cats were fixed before I got them from the pound. They were a little
weird at first, with some hissing and sneak attacks, then they got
along pretty well, sometimes playing chase and so forth.

A few weeks ago they started doing the weirdest thing--they are mating, is
what it looks like. He bites the back of Kissy's neck and she yowls,
then after a little tussle ... they "go at it." Has anyone every seen
this before? TIA Ronald in Tulsa