Hi Narendra,
DockingManager gets the value for DockingWindow label from the Name Property of the control if we have not specified it explicitly(Using SetDockLabel method). So when we create new instances of the control, we should specify the name for that instance.
Please take a look at this
sample developed in version 3.3 and let me know if it meets your requirements.
We appreciate your interest in Syncfusion products.
Thanks,
Vijay