Why would someone fake a modern Walther PPK?
There are War time PPs and PPKs with spurious markings to turn a 500 dollar gun into a 2000 dollar gun, but other wise,no. After Walther stopped making the PP and PPK in 1999, Interarms, which had been importing them had them assembly in the states. Walther would not allow them to continue with the old series numbers, so your number is simply a new serial number series used by Interarms. It can't be found in most Walther books because all the research is on the German and French ( under contract ) Walthers. There is very little collector interest in modern PPs and PPKs. Now S&W is producing them. You have a very fine firearm, enjoy.