Cron2 unique option not working as expected

[taifu]

I am using uWSGI with Django, and I configured a cron2 line in my vassal to run a management command every 5 minutes. I enabled the unique option to ensure the command does not run concurrently, as it sometimes takes longer than 5 minutes to complete.

However, I discovered that the unique option does not work as expected. To confirm this, I wrote a simple management command that writes to a file and scheduled it to run every minute. Here's the output I observed:

PID 5925 ============
PID 5925 Parent PID 5924
PID 5925 Worker PID 32284
PID 5925 Sleep 90
PID 6068 ============
PID 6068 Parent PID 6067
PID 6068 Worker PID 32284
PID 6068 Sleep 90
PID 5925 Exiting
PID 6068 Exiting

As you can see, process 6068 starts executing before process 5925 has exited.

Could it be that I have two workers executing the command concurrently?