Cisco is a famous example. They were founded to build a clone of the beloved PDP-10 mainframe. To bring in some cash they made copies of the stanford LAN routers the team had designed and built at Stanford. Turns out a lot of people wanted networking gear.
Years later some of the founders founded XKL to make a PDP-10 clone.
Years later some of the founders founded XKL to make a PDP-10 clone.