[16.0] OwlError: duplicate key in error message

[kmagusiak]

Module

mail_tracking

Describe the bug

When opening a form which has multiple failed messages to retry, we get an error.

UncaughtPromiseError > OwlError
Uncaught Promise > Got duplicate key in t-foreach: undefined
OwlError: Got duplicate key in t-foreach: undefined
    at MessagingClass.template (eval at compile (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:2057:374), <anonymous>:249:51)
    at node.renderFn (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:1613:210)
    at node.renderFn (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:1614:207)
    at Fiber._render (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:1496:96)
    at Fiber.render (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:1495:6)
    at ComponentNode.render (https://www.edi.be/web/assets/1630502-f13e9bb/web.assets_common.min.js:1571:56)

What would be your expected behavior in this case? No errors

To Reproduce

Affected versions: 16.0

Steps to reproduce the behavior:

1. Find an object with multiple failed messages
2. Open the form view

Expected behavior

Additional context