How to stop code generator in designer in this case-Collection of common programming errors

I am creating a custom control derived from ComboBox. I add some items to custom control in constructor of control. // this code is sample public MyCustomControl { this.Items.Add(“test1”); this.Items.Add(“test2”); } When I drag this custom control to my form, designer auto-generate the code: // this code in Form1.Designer.cs this.mycustomControls.Items.AddRange(new object[] {             “test1”,             “test2”}); When this custom control display on Form1, will have 4 items: test1 test2 test1 test2 This problem cause duplication.

Please help me how to solve this problem, I don’t want designer auto-generate these codes. Thanks.