I took a look at the VC-ClusterMapping.txt (as the warning says) within one of your previous results files.
This warning appears for a few reasons:
1. Host 10.1.12.66 has a VM named OmniStackVC-10-1-12-67
2. Host 10.1.12.68 has a VM named OmniStackVC-10-1-12-69
3. You're using the same client cluster as your server (SUT) cluster.