Jobs run after editing duplicate

I have some scheduled duplicate-to-tape jobs that are set to run on a given day and use the last full backup. I just edited to change some from Tues/Wed etc on the 2nd week of the month to the first week of the month (so they'll run tomorrow instead of next week). I only changed the schedule for the dedup to tape stage, not the original full backup stage, but the full backup started for most of these jobs when I saved the edit.

Any idea why this would happen, or what I can do to avoid in the future? I don't want to have full jobs start during business hours, but I don't want to cancel the ones that started because I don't want a cancelled backup to be the reference for my dedup to tape.

Thanks.