Was it a big sensation when McLaren signed both Senna and Prost?

Answer 1

Yes it was. Senna and Prost were sworn enemies and they both liked to win. They would go at each other and that's why it was such a controversy. Besides, they were THE two biggest names in F1 at that time and usually when you have two big names, and two death enemies you tend to cause a big sensation because not only does it cause controversy in the sense of wondering if the team will work, but it also creates better track battles considering they are both in the same car, and everybody wanted to see what sort of crash they would cause next and who would win, etc.

Answer 2

Yes it definitely was! One of the most perfect race cars for the rules, the McLaren MP 4/4, was almost undefeated for the entire season, except for one race where Senna and Prost took each other out while fighting for the lead.