Same CommandArgument for two different linkbutton

Question

First I gave to my first button the CommandArguments

btnDateModif.CommandArgument = hebergement.Attributes["IdInterne"].Value;

Then I'm using the button like this

 protected void BtnModifDate_Click(object sender, CommandEventArgs e)
        {
            PanelModifDate.Visible = true;
            PanelHebergement.Visible = false;
        }

        protected void BtnEnregistreDate_Click(object sender, CommandEventArgs e)
        {
            CheckValidDate();
            PanelModifDate.Visible = false;
            PanelHebergement.Visible = true;
        }

My question is how I can give the CommandArgument of the first button to the other one ?