When you import a single ICal file, it adds the respective appointments without clearing the already existing ones. However, you can't distinguish how two appointments are created or from which file they have been imported. The import functionality is available on RadScheduler
level, not per each resource. Hence, you can't import a specific ICal file for a certain resource.
I can suggest you consider import/export functionality from a custom file. Thus, you can implement the exact behavior that you want. In addition, you have full control on how to parse the passed data and create the respective appointments. The following help article demonstrates a sample approach. feel free to extend the example and achieve the requirement that you have: https://docs.telerik.com/devtools/winforms/controls/scheduler/importing-and-exporting-appointments/export-to-a-custom-file
I hope this information helps. If you need any further assistance please don't hesitate to contact me.
Dess | Tech Support Engineer, Sr.
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