... you need to tell us which 650GS the Single or the Twin; both had hard luggage as an optional extra, both were 'Vario' type i.e. expandable. The single requires mounting mushrooms and a lower rail, the twin much the same although I haven't looked too closely as the Jaqbike came pre-mounted

Those for the single also had a pretty ornamental alloy 'skin' with the same impact resistance as treacle toffee
As far as I'm aware, the two sets are not interchangeable