A grid in a RadAjaxPanel will fire several requests when exporting if there is a RadAjaxManager on the page as well.

Stems from the _setupExclusionFilters function where each RadAjaxControl adds as a handler to Sys.WebForms.PageRequestManager.getInstance().add_initializeRequest which does a  sender._form.submit(); and gets called in the initialize method of the control.

The resolution is to use only RadAjaxManager to AJAX-enable complex pages that require the built-in exports as well and make sure to remove all RadAjaxPanel instances. This is the better approach anyway: http://docs.telerik.com/devtools/aspnet-ajax/controls/ajaxmanager/troubleshooting/controls-wrapped-in-ajaxpanel-and-added-to-ajaxmanager-settings

Repro and example solutions are added in the file attached below.