Allocating 2 CPU for a VM

Iam vmware conultant for a coporate organisation, i would like to know what are the disadvatanges of adding 2 CPU on 1 VM for 2 node VM cluster example, cluster has 10 VMs and i add 2 CPU to one or two VM will this make the cluster inconsistent. 

I can see increase in performance of those VM.. not sure if this will affect overall cluster perfomance.

thank you for thie facility…

regards

shravan