Duplicate Call issue

I seem to have an issue where by when a call is made, which gets routed over a SIP trunk, after the caller (behind my freepbx) hangs up, the callee’s phone starts to ring again.

I am using Asterisk 13.3.2 with chan_sip and have the “Extension routing” module installed to send certain extensions down different routes.

An example of a call doing this is as below, I’ve replaced the called number with 123456 and my trunk cid with 654321:

on pastebin, id: YszC0Yg9

Any advice would be appreciated.