Normally, MultiPing only sends the data that caused the alert to fire, and if it's already sent you an email, it will only send new alert-causing data since the previous email went out.

What alert conditions are you using, and how do you have the alert event configured? If you send your alerts.ini and multiping.ini files from your MultiPing directory to support@multiping.com, and then let us know (here or via email) how you'd like things to work, we can help guide you to how to configure things correctly. We'll respond back here with an answer.