VMX_REPEAT Freepbx interface 6.12.65-19

I have a couple of Freepbx installs. Both are version 6.12.65-19

One of them repeats the voicemail greeting twice.
I noticed that VMX_REPEAT=2 in that PBX. However, I know if I change extensions_additional.conf it will be overwritten.
So what I would like to know is, where is the VMX_REPEAT setting in freepbx?

Thank you