If they're sharing a BindingSource
, then changing the value in one control will change the value in the other control as well.
When you change the value in the second ComboBox
, the value in the first ComboBox
changes too, which fires its SelectedIndexChanged
event.
Create a separate BindingSource
for each control, or if it's a collection, try just assigning the collection directly to each ComboBox
.