One-time CC: CheckBox "All recipients" not working correctly

I am reporting a bug. When CheckBox for “All recipients” is true then I see Cc recipient three times, always last recipient is three times. And in the log of RT or header of sended mail is recipient three times. My colleagues have discovered a problem on RT 5.0.1 and i tested it on my testing instance of RT 5.0.1. Thank you.

Log from RT:
From oracle@rt2.local Fri Aug 20 13:08:18 2021
Return-Path: oracle@rt2.local
X-Original-To: test2@helpdesk.local
Delivered-To: test2@helpdesk.local
Received: by rt2.local (Postfix, from userid 1001)
id 7E6F01076D9D; Fri, 20 Aug 2021 13:08:18 +0200 (CEST)
CC: test2@helpdesk.local, test2@helpdesk.local, site@helpdesk.local, test2@helpdesk.local
X-RT-Ticket: helpdesk.local #18
From: “Enoch Root via RT” <>
X-RT-Originator: root@localhost
Subject: [helpdesk.local #18] Test1
X-RT-Loop-Prevention: helpdesk.local
X-Managed-BY: RT 5.0.1 (
Content-Type: multipart/alternative;

Email header:

There is printscreenshot from RT:

Log from RT:
Aug 20 13:08:18 rt2.local RT[1631]: [1631] #18/482 - Scrip 4 On Correspond Notify Other Recipients
Aug 20 13:08:18 rt2.local RT[1631]: [1631] sent Cc: test2@helpdesk.local, test2@helpdesk.local, site@helpdesk.local, test2@helpdesk.local