Hello Wiek
It is almost 100% safe to say that there were no Italian Fw 190 fighters over Dieppe on 19 August 1942. This almost certainly is one of the very common misidentifications that occur in the heat of battle. Andrew Arthy has a very nice article on the role played by the Fw 190 units over Dieppe at
http://fw190.hobbyvista.com/dieppe.htm that you may or may not yet know about which is very complete including victory and loss lists and an Order of Battle of the Luftwaffe units involved. I hope that this may help you out a little.
Horrido!
Leo