Does scheduler.cron de-duplicate jobs with the same id?

[kennysong]

If I run scheduler.cron() twice with the same id argument, the job is only scheduled once.

This is great, but it's not documented anywhere. This old issue also seems to contradict what I'm seeing.

Can someone confirm that the scheduler actually de-duplicates cron jobs with the same id?

[phauch]

This also works for scheduler.schedule()
Would be nice if this was documented anywhere :-)

[demux]

Also, if I don't specify an id how is the id generated? Is it deterministic and based on the func argument?
i.e. do I have to specify id in order to avoid duplication?