My preferred version is
Katharine, closely followed by
Catherine. I would use either as a mn, precisely because of the nn issue. First there were edge-to-edge
Cathy people, then came the
Kate outbreak, then various forms of
Caitlyn ... what next? I love
Kitty, but not if there would be 11 000 000 other ones, jostling for position. And I don't enjoy
Rina at all; it might never happen, but then again, it might.