Hello Dawid Wódkowski,
Thank you for writing.
By default, the selected index of a RadListContol, binded to a binding source, reacts when the Current of the binding source is changed. Since your both controls are binded to the same binding source, a user selection in the first control will be reflected by the second control and vise versa. In order to solve your issue, you should create two distinct binding sources and set them to your RadListControl instances.
If you have other questions, feel free to write back.
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