>>prefsRetailViewModel.AvailableTrackingColumns = this.trackingLookupOrderColumns.Except(prefsRetailViewModel.AssignedTrackingColumns);
>>>>Dictionary<string, string>>>
public class StringDictionaryComparer : IEqualityComparer<KeyValuePair<string,string>> > { > public bool Equals (KeyValuePair<string, string> a , KeyValuePair<string, string> b) > { > return a.Key == b.Key; > } > > public int GetHashCode(KeyValuePair<string, string> item) > { > return item.GetHashCode(); > } > }Your code should then work (assuming you only need to check the key)