Is it OK to mentally multi-task during vipassana meditation? It appears that I have found it possible to focus both on the breath (as a meditation object) and to be aware of a bit of a train of thought. 

Is this acceptable, or unacceptable, or should it be avoided? Or, is it perhaps simply varying "snippets" of mind-moments where I am slipping in and out of bare awareness of the meditation object?
Multi-tasking is an illusion... I have read that the mind and the senses are like a monkey sticking its head out six different windows rapidly in succession.  

A great lama once told me that trying to solve a puzzle when you sit down to meditate is in actuality making another samsara.