Hi Stephan,
Leaving WW II out of this...you should try to pick up a copy of Norman Franks' excellent book:
Who Downed the Aces in WWI? from Grub Street, 1996. Norman tackles the job of uncovering who shot down various aces throughout the war in a thorough fashion. Russ Gannon could no doubt add a lot to Norman's research and refute or contradict some of it too!
Jon Guttman's ever-expanding range of "Duel" titles for Osprey also covers this topic.
A few comments on your comments:
It's now quite doubtful that Fonck "got" Wissemann (and there are many who doubt that Wissemann 'got' Guynemer!). British historians prefer to give credit to 56 Sqdn's Hoidge or Bowman.
One interesting topic would be
Paul Billik of Jasta 7, 12 and 52. On 30 April 1917 he (apparently) shot down J J "Jack" Malone of No 3 Naval.
On 19 May 1918, Billik is credited by some with shooting down Albert D Carter DSO of No. 19 Sqdn. However, Carter always vehemently stated he had been forced down behind German lines by engine trouble, IIRC (see Stew Taylor's recent superb article).
On 1 June 1918, Billik seems to have shot down Capt Cairnes of No 74 Sqdn.
On 8 July, Billik apparently shot down Capt.
Arthur Claydon of No 32 Sqdn. Billik himself was shot down and captured on 10 August 1918 (possibly by 32 Sqdn), thus he was 'robbed' of his chance of winning the PLM.
There are many other interesting possibilities to argue about.
Georg von Hantelmann definitely shot down
David Putnam, and seems to have downed
Joseph Wehner as well. He is often credited with downing
Maurice Boyau on 16 September 1918, but French authorities say it's much more likley that Boyau fell to German ground fire with Hantelmann getting the credit.
The deadly
Franz Buechner of Jasta 13 seems to have accounted for Major Callaghan MC, and possibly Lt. M S "Sammy" Taylor of No 209 Sqdn. Taylor himself had apparently downed
Hans Weiss earlier.
The list goes on and on....