EDIT: Question is solved, it was my mistake, i simply used the wrong cron settings. I assumed "* 2 * * *" would only run once per day at 2, but in fact it runs every minute past the hour 2. So Kubernetes behaves correctly.

I keep having multiple jobs running at one cron execution point. But it seems only if those jobs have a very short runtime. Any idea why this happens and how I can prevent it? I use concurrencyPolicy: Forbid, backoffLimit: 0 and restartPolicy: Never.

Example for a cron job that is supposed to run once per day, but runs multiple times just after its scheduled run time:

job-1554346620                   1/1           11s        4h42m   
job-1554346680                   1/1           11s        4h41m                     
job-1554346740                   1/1           10s        4h40m 

Relevant config:

apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: job
spec:
  schedule: "* 2 * * *"
  concurrencyPolicy: Forbid
  jobTemplate:
    spec:
      template:
        spec:
          containers:
            - name: job
              image: job_image:latest
              command: ["rake", "run_job"]
          restartPolicy: Never
          imagePullSecrets:
            - name: regcred
      backoffLimit: 0