Cassandra_stress and Redis use more VMs than requested machine_type

Running cassandra_stress or redis on a target with 4 VMs produces an error that CPUS are exceeded, limit 8. The limit 8 is because I using a GCS trial which limits to 8. But in any case the benchmark is using more VMs than is configured for the test run.
I ran cassandra_stress and redis successfully on a GCS 1 VM systems, but they fail on 4 and 8.