Our dataextensions might have the same email address with different subscriber keys, and when i send multiple emails a day to different data extension, i am sending multiple emails to those emails addresses. I am trying to avoid sending multiple emails and thinking to use AMPScript in Advanced Exclusion section. Any ideas what that script should be?
You could try using SendLog DE to store the emails for each send - and then have a filtered Data Extension which would give you the emails for a particular day (time period) - then in the Exclusion Script you could use the LookUpRows function to see if there's already 1 or more that match with the email - if count > 0, then Exclusion script shall evaluate to True and the email could be excluded from the send. You may need to figure out an automation to run the Filter Activity and refresh the Filtered DE to always shows the latest SendLog email ids for the specific day.