Dish Toggle Variation ?

I have noticed a luger on my cover of Aaron Davis' book, The Luger Handbook, that has a dish toggle but with an inlaid, vertical bar running through the toggle knobs.


On GunsAmerica, ad # GA-976110956 ($ 5,000), a 1902 luger is shown with this same "old" toggle variation.


Can anyone explain this toggle variation ? Is it something from the "transition" luger period before the -08 design was finalized ? Should this inlaid bar be "straw" finished ?


Thanks in advance for your help...


Pete