Let's cover all our bases. :)

The hospital scene with Kirkland and Jason Lennon is one of the most PUZZLING scenes in the whole series.
There are two possibilities:
1)It is Bob Kirkland at the scene.So, what do we got?Kirkland asks if Lennon recognizes him.That makes total sense by the time he has a twin brother that he thinks Red John killed.Depending on Lennon's answer he would be able to get the information whether his brother is killed or not by Red John.
Kirkland: "Do you recognize me?Have you seen me before?Look close"
Lennon answers: "No"
Kirkland: "Are you sure?It's important."
Lennon: "Yes"
After that he takes out the injection and kills Lennon.WHY?We already know that Kirkland chases Red John as well, so killing a key-person to the case makes no sense.Some could say He wanted to make sure that Jane would not have the information Lennon could provide.But still, watch the S06EP04, Bob Kirkland tortures people and is being so aggressive, so determined, so sure for himself.He MUST do it till the end.At least he could ask him a couple of questions about Red John before killing him.THAT MAKES NO SENSE.

2)It is Michael Kirkland at the scene.What we got there?Killing Lennon makes TOTAL sense, for keeping away from Jane all the things that Lennon knew.So why is it so DAMN important about Lennon recognizing him or not?What's the point?I mean, if he was Red John, Lennon's answer is weird.Some might say he has lost his memory.That's impossible.Here's why:
Kirkland: 'You are in Sacramento Hospital, you've been shot.Do you remember that?"
Lennon: "Lorelei Martins"
Kirkland: "Correct.Your mind is CLEAR"
Some other might say that Lennon indeed recognized Kirkland as being Red John, and he answered "No" because he was afraid that if he would be able to recognize RJ, he must die.But that theory is rejected too.Why?Look at the expression on the face of Lennon.He clearly seems troubled trying to identify the guy that stands in front of him.
Last possibility:Lennon knows that Red John has a twin brother, and he answers no because he is not sure if the person that he is talking to is either Red John or his twin brother.In my opinion, there are a lot of scenes that puzzle the audience, and Bruno Heller is obligated to give the answers.