Importing appointments from SugarCRM

Hi,

What's the best way to test if a given appointement hasn't been created twice ? I already have create the necessary javascript code to import and create appointments in zimbra that relate to appointemnts in sugarcrm by user action (click on zimlet). But if the user clicks again, the script will import the same appointments again and they'll be created as many times as that zimlet is invoked.

Do you have any suggestion on how to create these appointments only once ?

Can I save some metadata inside the zimbra appointments that I can check to not create a copy of it ?

Thanks for your thoughtful ideas.