In a multiple-impact collision, airbags are designed to deploy if the first impact when severe enough for the computer to active the system. In the example below, if the first collision were severe enough to activate the front airbags, those same airbags cannot activate again. Airbags are designed for use once.
Every wonder why at some scenes the airbags are not deployed?
Thanks to Nissan for having this information available in their Consumer Safety & Air Bag Information Guide.