Entity Framework Error : Violation of PRIMARY KEY constraint . Cannot insert duplicate key in ASP.Net

Hello I am updating a few different tables with the same data from my main table, but after inserting say 4 or 5 records I get the above error for one of the tables, here is my code.

public static void InsertSnookerMainTable(string FirstName, string LastName, string Team)
{
    try
    {
        using (var DB = new FinalWringtonValeDB())
        {

            BilliardBreaks SnookerMainTable = new BilliardBreaks();
            SnookerMainTable.FirstName = FirstName;
            SnookerMainTable.LastName = LastName;


            Div1Breaks Div1Breaks = new Div1Breaks();
            Div1Breaks.FirstName = FirstName;
            Div1Breaks.LastName = LastName;

            Div2Breaks Div2Breaks = new Div2Breaks();
            Div2Breaks.FirstName = FirstName;
            Div2Breaks.LastName = LastName;

            Contacts Contact = new Contacts();
            Contact.FirstName = FirstName;
            Contact.LastName = LastName;

            DB.SnookerHandicaps.Add(SnookerMainTable);
            DB.Div1Breaks.Add(Div1Breaks);
            DB.Div2Breaks.Add(Div2Breaks);
            DB.Contacts.Add(Contact);
            DB.SaveChanges();
        }
    }
    catch (Exception ex)
    {
        Error:- ** Violation of PRIMARY KEY constraint . Cannot insert duplicate key ** 
        return;
    }
}