Problem between a "log2ram-daily.timer" and its "override.conf" file

I am getting a problem between a "log2ram-daily.timer" and its "override.conf" file and I am not sure if it is because of syntax incompatibility or what. This is what I am doing:

Raspian on Pi3B+

The "log2ram-daily.timer" contains :

[Unit]
Description=Daily Log2Ram writing activities

[Timer]
OnCalendar=*-*-* 23:55:00
Persistent=true

[Install]
WantedBy=timers.target

Its "override.conf" file contains :

[Timer]
OnCalendar=Mon *-*-* 23:50:00

But the result is not as I want...

When I "systemctl status log2ram-daily.timer", the trigger indicates

Trigger: Fri 2021-07-30 23:55:00 CEST; 19h left

Not as expected in the override.conf...

In my troubleshooting, I modified the file "log2ram-daily.timer", by adding "Mon":

[Unit]
Description=Daily Log2Ram writing activities

[Timer]
OnCalendar=Mon *-*-* 23:55:00
Persistent=true

[Install]
WantedBy=timers.target

And...

systemctl status log2ram-daily.timer
Trigger: Mon 2021-08-02 23:50:00 CEST; 3 days left

The override.conf is now well loaded! But why? Syntax incompatibility?!

Solution

I found the solution, in the "override.conf" just add an empty directive before, because otherwise it will be repeated.

[Timer]
OnCalendar=
OnCalendar=Mon *-*-* 23:50:00