If a man causes another man to do something wrong, who bears the greater guilt?

That would depend entirely on the definition of "causes" that you are using. Causes by lying to him? Causes by holding a gun to his head? Causes by threatening his family? Causes by offering him a lot of money?

I don't know.  They might be equally guilty.

That's a judgment call, best left up to Jesus Christ. But, there's plenty of blame on both parties.

The man that deliberately causes the other man to do what is wrong is first off at fault.  But unless the other man is deceived in other words he doesn't know that he's doing something wrong he bears guilt also because he is a man he is the spiritual leader of himself.

And as such has the duty of discerning what is good and what is bad.

This is not the perfect plan of God God never intended man to be able to discern good and evil for himself that was the original sin in the garden of Eden but now we have it we begged for it and now we have to live with it

Mar 9:42  “Whoever causes one of these little ones who believe in me to sin, it would be better for him if a great millstone were hung around his neck and he were thrown into the sea. 

Both will be guilty but the one who causes someone else to do wrong will have the greater guilt, I believe.

Whichever one is on top.

The guy who did it. Courts don't recognise coercive persuasion as a defence otherwise it would be almost impossible to get a conviction on acts of terror or war crimes.. there's no such thing as being brainwashed, it's always a choice..

That is called scandal. It is the greater sin. Jesus said (Mk. 9:42), "But if anyone causes one of these little ones who believe in Me to stumble, it would be better for him to have a large millstone hung around his neck and to be thrown into the sea."

The guilt is on the one that did the deed.  It is a choice.