When attempting to replicate a virtual machine from one host to another within the same cluster using the same Virtual Appliance the following warning is seen in the summary of the replication wizard:

This warning appears to inform the user that while the replication job may complete successfully, it may not be as efficient as using a Virtual appliance on source and target host.
Virtual Appliance per cluster is a new feature in vRanger 5.4, its purpose is for hosts to share a Virtual Appliance within a cluster. The Virtual Appliance was designed to be shared by hosts within a source cluster or target cluster.
If you are replicating within a cluster from one host to another, deploy virtual appliances to each host. This will ensure more optimal replication speeds and resources will be shared between the two hosts.