If Bofoi is a robotic genius that could make super advanced robots, it would make more sense for him to make multiple super robots instead of just making one (Metal Knight) and using the rest of his resources to make generic combat minions.
Drive Knight is either his other alter ego that he uses to collect information as a combat scout, without revealing the tech for his more advanced super robot (Metal Knight), or Drive Knight was a product of a sentient AI robot that rebelled against Bofoi for one reason or another.