Remove duplicate values from dropdownlist

Sir,

Not working... I am loading dropdownlist only at page load event

like this

IF(!Page.ISPostBack)

{

LoadDropdown();

}

Then check your data for duplicate

Sir,

I have checked properly and there are no duplicates

Give me the LoadDropDown function. Also how many times you call it?

I call this method only at page load event. Here is the code below:

 private void load_dropdownlist()
    {

        DataSet ds1, ds2, ds3, d4 = new DataSet();
        //load Project name from project details table
        ds1 = PopulateControlsCls.LoadDataSet("Select ProjectID,ProjectName from ProjectDetailsMaster");
        drpprojname.Items.Clear();
        drpprojname.DataSource = ds1.Tables[0];
        drpprojname.DataValueField = "ProjectID";
        drpprojname.DataTextField = "ProjectName";
       
        drpprojname.DataBind();
        drpprojname.Items.Insert(0, new ListItem("-Select Project-","0"));
        ////load module name from module_master table
        ds2 = PopulateControlsCls.LoadDataSet("Select ModuleID,Module from module_master");
        drpmodule.Items.Clear();
        drpmodule.DataSource = ds2.Tables[0];
        drpmodule.DataValueField = "ModuleID";
        drpmodule.DataTextField = "Module";
       
        drpmodule.DataBind();
        drpmodule.Items.Insert(0,new ListItem("-Select Module-","0"));
        ////load user/employee name from login_master table
        ds3 = PopulateControlsCls.LoadDataSet("Select LoginID,FName +'  ' + LName as Name from login_master");
        drpemployee.Items.Clear();
        drpemployee.DataSource = ds3.Tables[0];
        drpemployee.DataValueField = "LoginID";
        drpemployee.DataTextField = "Name";
       
        drpemployee.DataBind();
        drpemployee.Items.Insert(0,new ListItem("-Assigned To-","0"));
        d4 = PopulateControlsCls.LoadDataSet("Select Taskid,Task from task_master where Module='"+drpmodule.SelectedValue+"' AND ProjectName='"+drpprojname.SelectedValue+"'");
        drptask.Items.Clear();
        drptask.DataSource = d4.Tables[0];
        drptask.DataValueField = "Taskid";
        drptask.DataTextField = "Task";
       
        drptask.DataBind();
        drptask.Items.Insert(0,new ListItem("-Select Task-","0"));
    }