I Agree With Alma - The Ending Where He Burned the Formula Was Better
Espionage during the cold war era was a foul nasty business and films of that period had no business sanitizing it (Martin Ritt's "Spy Who Came In From the Cold" is an excellent example of the genre).
So, why would Michael burn the formula at the end of the film after all the trouble obtaining it? Probably a feeling of guilt. Professor Michael Armstrong and his female accomplice brutally tortured and murdered Hermann Gromek who was only doing his job, he also put a lot of other people's lives in danger - all in order to lie, cheat and steal a formula from a fellow scientist who trusted him. In a deleted scene at a factory canteen, Gromek's older brother tells Michael that Gromek was a married man with 3 children.