Android : Why am I getting duplicate records from this method?

I am trying to insert some coordinates (from a txt-file) from an app using a servlet into a table named myTable in a phpMyAdmin using this statement (I am sending this statement as a string using AsyncTask):

INSERT INTO myTable(latitude, longitude) VALUES (" + coordinate.getLatitude()
                            + "," + coordinate.getLongitude() + ")";

The method I used is this one:

public boolean insertValuesToMyTable(String insertToTab) {
        try {
            connec = this.getConnection();
            st = connec.createStatement();
            if (connec != null) {
                st.executeUpdate(insertToTab);
                if (st.executeUpdate(insertToTab) > 0)
                    return true;
                return false;
            } else {
                System.err.println("No database connection, ...");
                return false;
            }
        } catch (Exception e) {
            System.err.println("Exception: " + e.getMessage());
            return true;
        } finally {
            try {
                //if (rs != null) rs.close(); //ResultSet
                if (st != null) st.close(); //Statment
                if (connec != null) con.close();
            } catch (SQLException sqle) {
                System.err.println("Inner SQLException: " + sqle.getMessage());
            }
        }
}

Everything is fine except that I am getting duplicate rows. For example for 2 points (22.2525, 56.5689) and (22.7812, 25.1144) from the file, it will be:

id latitude longitude
1  22.2525  56.5689
2  22.2525  56.5689
3  22.7812  25.1144
4  22.7812  25.1144

Normally, it should be:

1  22.2525  56.5689
2  22.7812  25.1144

What am I doing wrong in my query?