We have a PBX that we are using the VmX locator on. It is working on unavailable and busy but when someone has a temp greeting enabled it plays the greeting two times.
It is enabled for Unavailable, Busy and Temp at the extension level.
When I go to Settings --> Voicemail Admin --> Dialplan Behavior we have it set to play once and retry once which are the lowest settings.
FreePBX - 12.0.52