1. The young man and The police officer were handcuffed together.

2. The police officer handcuffed the young man and himself.

(Does #2 the active voice of #1?)

3. The two men were handcuffed together.
4. The police officer handcuffed the two men.
5. One of the two men handcuffed the young men and himself.
(What is the active voice of #3?)

2 is the active voice of 1, yes.

3 and 4 are the passive and active pair. 5 is setting up a different set of actions.