If I understand you correctly you have 12 licenses for 1 CPU each!? In order to assign a license to a host the CPU capacity of the license has to be equal or greater than the CPU count of the host. You can combine the licenses in the My VMware portal.
Btw. for two host with 2 CPUs each, you only need 4 CPU licenses (not 12), as the CPUs/sockets are licensed, not the cores.
André