[BG95] Causes of retry for MQTT publish messages

I am using BG95 to publish MQTT messages.
The same message was sent three times with an interval of several tens of msec.
It only happens very occasionally.
These messages have DUP flag.

The timeout settings are 15 seconds and 3 times.

Would BG95 retry for any reason other than “timeout”?
If so, is there a possibility of retries at intervals of tens of msec?

Thanks for the help.

If BG95 retries, will DUP flag in MQTT publish message be enabled?

This BG95 is BG95M6.
The firmware version is BG95M6LAR02A02_01.008.01.008.