AMPScript creating multiple entries

%%[set @id = _subscriberkeyset @communities = 'Community-id' /* replace this id with your community ID */var @createdemographicset @createdemographic = CreateSalesforceObject('Demographics__c', 5,'Contact__c', @id,'Community__c', @communities,'Answer__c', 'Yes','Name', 'Requested a call back?','MCSource__c', 'CALLBACK-6JUNE')]%%

This is my AMPSCRIPT to create a new record for my custom object 'Demographics'. This creates multiple entries when the user visits the cloud page. How can I limit it to just one entry per contact?