I get the sense that the cartoonist couldn't decide which punchline was better, so he decided to use both. But that's cheating. Part of working in a medium with severe space limitations is being a ruthless editor. Sometimes you have to cut good stuff so that the stuff you do use is more affecting. Not that there aren't times when cheating can pay off. This just isn't one of those cases.
And just in case anyone's wondering, personally, I would have gone with the first punchline. But I'm a big fan of image-based humor, so I'm a little biased.