Can you have two posts for a crown built up, without a root canal?

It may be that you had two pins placed in your tooth. Pins are small post like structures placed into your tooth where there is significant loss of structure. They help hold in your filling or crown build up. They can be placed in vital teeth without root canals as they are placed into the tooth dentin away from the nerve.Posts however are longer structures placed into the root canal system of a tooth so it does require a root canal to have been done first. This is used when a root canal treated tooth has minimal tooth structure left and again functions to hold in the filling build up and eventually the crown over top. I hope this helps clarify.  

You might be thinking of pins rather than posts. Posts are larger and are put down into a root canal to give a better hold for a build up and crown. Pins are smaller and are screwed into the tooth in areas where lots of tooth is missing again to give retention or hold for a buildup. Oftentimes you need more than one pin to support the buildup