If an automated email has been sent to the candidate then the candidate is not able to receive that email/text message a second time for the same job. Candidates will only receive an email/text message through the same or another automation one time per job.
If an automation has been triggered by a candidate movement, but the email/text message has been canceled or the candidate moved out of the stage, then the automation will trigger again if the candidate has been moved back to the stage.