"Not Junk" button sends email to a different internal address

When a junk email is marked as "not junk" it is sent to a different internal address with an ID tag added to the start of the subject line.
I am struggling to figure out why this is happening and how to fix it.

Example:
Staff member 1 receives an email with the subject "xyz" that is filtered to the junk box. They mark the message as "not junk" staff member 2 receives the same email but with the subject "2|cac58361-84a8-4d47-520a-08dc1c73f2b5| insert original sender email address here|(xyz)"

If anyone could shed some light on why this is happening I would be very grateful.