Multiple radio button using a single Function but differnt behaviour

on .aspx page :
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then write following code on .aspx.cs page :
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protected void RadioButton1_CheckedChanged(object sender, EventArgs e)
{
RadioButton rbtCommon = (RadioButton)sender;
if (rbtCommon.Checked == true)
Label1.Text = "i am in " + rbtCommon.ID.ToString();
}