The SelectedIndexChanged is not supposed to fire if, as the name of the event speaks of itself, the selected index is not changed. Could you please clarify which event, client or server, you have troubles with?
For more information on both, you could refer to the online documentation:
If you continue to have troubles, I encourage you to open a support ticket on this matter where you can send us a sample project with this behavior replicated in it. This way we will be able to troubleshoot the issues locally and provide you with an accurate answer.
All the best,
the Telerik team
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