In order to use the multiple-multiple inserts on the page you will need to ensure that you have your records working in advance, then you need to apply the repeat selection tool to print out all of the records form that recordset and repeat any form elements like the checkbox.
If you have all of the repeat selections and recordsets working correctly on the page then when the multiple inserts are triggered it should process each one of them.
If you are experiencing any problems with this or if you cannot get the server behaviors to apply to the page correctly let us know and also post back with the page in question so that we can get a feel for what you are experiencing.
