Yes, Brenner and Steinmetz are the same person. Brenner uses his Steinmetz disguise with Melville because he wants to throw su****ion on Steinmetz. He rigs the car to blow up and knows that Melville will report him to the police, complete with a sketch. All of this is done in an attempt to throw the police (Columbo) and The Director off the trail.
Glad I could help. Columbo is my favorite show, as well. There were many decent shows from the 70s, but this one had superior qualities, which has led to its lasting legacy.
Since I have you, who is Melville and how does he fit in the story? On the beach there talking about if I remember $350,000, what the details of who’s paying the money and who’s getting it??