Problem with repeating combo box items

[ChrisHunter]

Hi I'm pritty new to C# I'm having trouble with items repeating in a combo box

This method gets the values from my table and stores it in the list of strings which it does fine . . . I think.

public class EditStates {
        public List<string> getStates(CEditStates ced)
        {
            string typeSelected = (string)ced.cb1.SelectedItem;
            string states = "SELECT State FROM MyTables.StateDefaults 
            WHERE ObjectTypeID = '" + typeSelected + "'";
            SqlCommand cmd = new SqlCommand(states, db.Connect());
            SqlDataReader reader;

            List<string> objStates = new List<string>();
            try
            {
                reader = cmd.ExecuteReader();
                while (reader.Read())
                {
                    objStates.Add(reader["State"].ToString());           
                }
                reader.Close();
            }
            catch
            {
                MessageBox.Show("Failed to retreive object states");
            }
            return objStates;
        }
   }

And this method changes the value of cbo2 and populates cbo3 (which has the repeated values) when cbo1 is changed.

public class CEditeStates {
        private void cbo1_SelectedIndexChanged(object sender, EventArgs e)
        {
            string newobjDesc = ed.getNewDesc(this);
            getObjectTypeState() method

            List<string> _objState = ed.getStates(this);
            if (cbo2.SelectedItem != null && cbo3.Items == null)
            {
                if (cbo2.SelectedItem.ToString() != newobjDesc)
                {
                    cboB2.SelectedItem = newobjDesc;

                    foreach (string str in _objState)
                    {
                        cbo3.Items.Add(str);
                    }
                }
            }
       }
   }

Can anyone see why cbo3 repeats the values ?
Thanks in advance

[lolafuertes]

I can only see that the problem will be on the _objState. Is the ed.getStates returnin duplicates?

Hope this helps