How to create check box run time

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C#

Hi every one i create check box in gridview on runtime.
But one problem i face i use check box when i checke the check box then datagridview fill with data and automatical create one checkbox in one row.
problem is that
when i uncheck the chekbox then datagrid view datasource is empaty and when i check the check box again then it create two check box with every row inside the grid view....
And when i again uncheck the check box and again checked the check box then it create three check box inside the grid view any one help me how can i stop the multiple check box that created inside the grid view.
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I want only one check box with all the rows

I try this code
this code is run when checkbox check sate is changed

What I have tried:

private void isactiveOffercheckBox_CheckedChanged(object sender, EventArgs e)
        {
            if (isactiveOffercheckBox.Checked == true)
            {
                OfferdataGridView.DataSource = null;
                OfferdataGridView.DataSource = GetofferfromDb();
                DataGridViewCheckBoxColumn chekbox = new DataGridViewCheckBoxColumn();
                chekbox.HeaderText = "chekbox";
                chekbox.Name = "chekbox";
                OfferdataGridView.Columns.Add(chekbox);               
                OfferdataGridView.Enabled = true;
                OfferdataGridView.Height = 146;               
            }
            else           
            {             
                OfferdataGridView.DataSource = null;
                OfferdataGridView.Enabled = false;                
            }
        }