I take klonopin and have experienced some odd things with it (like 1 mg in the daytime will make me incredibly sleepy but 3 mg at bedtime has less effect) so I was interested in what you were asking.

I found this info on the drugs.com site (one I've seen my pharmacist check.) Some other reading seems to suggest that mixing any kind of benzo with Lamictal is going to do similar things. There was also some info about glutamate & GABA with Lamictal and klonopin on crazymeds.com but I couldn't understand it.

The general vibe I got was to be very careful mixing benzos and Lamictal.