[StraDuc]

Do you have the old cap and lock? It is appears to be easy (2 screws) to switch the lock cylinder over to the new cap. If you don't have the old one you could probably remove the new lock cylinder and take it to a competent locksmith who could change the pins to match the ignition key. Two keys would be a PIA. Because I use a tank bag I have a flush mount billet job with a screw on cap...no key needed. One more option.

https://www.slingshotracing.net/catalog/ducati-749999multistradagtsport-cnc-gas-cap-p-64.html