There are MacKenzies who spell it Mackenzie - I have some on my mother's side. It comes in handy when I want to tell my relatives apart. Kenzie is normally anglicized as Kenneth (or Cannice in Kilkenny).

Beth is the Gaelic "beatha" - life, and the Mormaers of Moray used mac (son of) and mal (follower of) almost interchangeably.