Collision on property error when creating a subwiki

STEPS TO REPRODUCE

1. Login as Admin
2. Create a subwiki with scope 'Both global and local users are available in the wiki' for example and mark it as template (that's how I've reproduced the issue last time)

EXPECTED RESULTS

The subwiki is created successfully without any errors.

ACTUAL RESULTS

There is an error related to collision found on a property:

Collision found on property [startDate] between from value [Mon Oct 19 14:59:13 EEST 2020] and to [Mon Oct 19 14:59:30 EEST 2020]

No errors in console.

The issue could not be reproduced consistently every time a wiki was created on 12.9 and 12.6.3 (marked as template or not) or created from a template (but only sometimes it seems - quite seldom) and it also couldn't be reproduced on XWiki 12.6.2.

However, on XWiki 13.7RC1 and 13.7 it reproduces consistently when creating a subwiki. Could not reproduce on XWiki 13.6.