As long as the new cluster is going into the same data center (meaning the vCenter data center entity as a hard requirement, and the same geographical site as an availability recommendation), you can manage multiple clusters from the existing VSMs. If the clusters are going to be running different versions of vSphere, double check the 1000V compatibility matrices to make sure you're okay.
You do have the option of deploying a new pair of VSMs within the existing DC for a new cluster, but it's not required.