Lolly and Frank,

Where does it indicate in the film that the hitmen were killed outside Fredo's house? Yeah, Deanna is babbling about people outside her window, but the place where these guys are found do not indicate it's outside Fredo's house.

To cut one man's throat, one person could get away with, but to cut two throats? Highly unlikely. Wouldn't the second hitman see what was happening to his accomplice?

The plot thickens.