Willian,
Conforme, voce descreveui está certo as contas e realmente está aparecendo errado.
Pergunta: Existe algum limit configurado nessa VM ?
Só para constar que você está certo - CPU Counters
Total amount of CPU resources of all hosts in the cluster. The maximum value is equal to the frequency of the processors multiplied by the number of cores.
totalmhz = CPU frequency x number of cores
For example, a cluster has two hosts, each of which has four CPUs that are 3GHz each, and one virtual machine that has two virtual CPUs.
VM totalmhz = 2 vCPUs x 3000MHz = 6000MHz
Host totalmhz = 4 CPUs x 3000MHz = 12000MHz
Cluster totalmhz = 2 x 4 x 3000MHz = 24000MHz