Well, the thing that is kind of fascinating about Congo Bongo, is that it may not be a knock off. There is some clues that it was developed by Ikegami Tsushinki. In the rom dump, there is "CONGRATULATION !IF YOU ANALYSE DIFFICULT THIS PROGRAM,WE WOULD TEACH YOU.*****TEL.TOKYO-JAPAN 044(244)2151 EXTENTION 304 SYSTEM DESIGN IKEGAMI CO. LIM." It was common at that time for the hardware manufacturer to program the game as well. It was also common to put messages like this in the code. Sort of a scouting technique. Ikegami Tsushinki settled out of court over the lawsuit that Nintendo used the Ikegami code for Donkey Kong Jr. All of this is uncertain. But strongly hinted. There is a chance that Ikegami Tsushinki is one of the biggest unsung heroes of gaming. Donkey Kong, Radar Scope, Zaxxon, etc.
But SEGA does a lot of "knock off" games. Golden Axe Warrior is probably my favorite.