The Thompson Twins, as they are known, are a favorite of
Tintin readers the world over. They've inspired the naming of a popular
rock group of the same name.
Ostensibly detectives working for Interpol and Scotland Yard, the twins are identical gents who wear black bowler hats and carry walking sticks. They have bushy mustaches and are quite good at getting everything wrong, although usually in a harmless or even helpful way. They serve as a better-humored Lestrade to Tintin's Sherlock Holmes.
They're famous for identifying themselves as 'With a P' or 'Without a P' by using hilarious clarifications: "With a 'p' as in Psychology" or "With a 'p' as in Pharaoh".
Homage to this was paid in no less different a medium than the movie Die Hard, which featured FBI agents named Johnson & Johnson, one black, the other caucasian. In addition to opening phone conversations with "This is Agent Johnson. No, the other one," they introduced themselves similarly: "I'm Special Agent Johnson. This is Agent Johnson. No relation."
In response to thbz's note below, Allan Thompson's name was changed to simply 'Allan' in the English versions. I don't think they gave us his first name, but 'Allan' is meant to be his last (family) name.