We have recently starting using A/B testing on date/time, subject line, from, etc. When testing the date/time I have been sending to 100% of the lead 50% in the morning and 50% at night. This email has a specific day of the week it needs to go out. We have noticed that someone (within our company) has been receiving the email multiple times to the same email address. We have checked and verified that the email is not in the system numerous times. Can anyone help me understand why this is happening? Is it because we are using 100% of the test sample size? Any ideas would be greatly appreciated.
When you say "multiple", do ou mean twice (once for each segment of the test) or more than twice (which would be really strange)?
Have you looked at the activity log of the lead in Marketo to check the email sends and which campaigns sent them? You may discover here that the email was sent by multiple campaigns.