Frindly fire was really rare during World war Two air fighting. Many times it was only fake friendly fire incident. Pilot didnt recognise enemy aircraft and didnt know what really happend.

I have something bigger here from ma academia.edu page.

The same could happend during Baders shot down. He was probably shot down by Bf 109F, not by Casson.

I have to say as war historian I am realy tired by fake friendly fire stories based on pilots not credible testimonies. Pilots testimonies, stories etc. are not reliable even during combat, two times more after landing and TEN times not reliable after months or even years. When you are as POW in camp, you just thinking what you should do, what you did wrong whole day. Over and over again. You want to be usefull and good warrior. You just want to appologise for being shot down and you desperately want to show your success. So, you could tell people, that you definitely shot down enemy plane before being shot down himself struggling for survival....!
As war historian you MUST be suspicious and do not believe everything you hear from pilots, even if you LOVE them personaly. Pilots have very difficult situation and canʼt see much from cockpit doing maneuvres. They will tell you incredible stories based on few seconds of combat. Do not believe them a word. You must compare stories and records. Construct your theories on paper, not on STORY told you by pilot. Only, and only if, everything match together, publish your version of events! And still its only possible version of combat. You cant be sure for 100 % even if records and claims match perfectly.

Do you want example? Could anybody blame F/Lt John Charles Dundas that by shouting "I've finished a 109—Whoopee!", he did shot down one of his friends from No. 609. Squadron? Could enybody say that? I wil NOT. Its nonsence, its assumption, its not historical. What really happened? Dundas was shooting, didnt hit, but saw plane falling down. Combat is so quick, that many pilots saw one plane going down and thinking "I just killed the enemy", and It was only one aeroplane. It could be FC fighter! Did they destroyed FC Spitfire? No! They just saw plane falling down.
During combat after 16.00 over Isle of Wight on 28th November 1940 no German fighter was even hit! No. 609 Squadron lost 4 planes.
Spitfire Mk.IIA X4590/PR-F P/O Alfred Keith Ogilvie (Yellow 3) unhurt - hit in fuselage and propeller by two cannon shells and landed at 16.55. Repaired and took off again with P/O Piotr „Osti‟ Ostaszewski-Ostoja on 12th December 1940 at 13.35.
Spitfire Mk.IA X4165/PR- P/O Janusz Żurakowski unhurt - hit by cannon shell into fuselage (left plate) and landed.
Spitfire Mk.IIA R6631/PR-Q P/O Paul Abbott Baillon KIA hit by Me 109 fire somewhere near Isle of Wight. Burried at Bayeux War Cemetery.
Spitfire Mk.IIA X4586/PR-D F/Lt John Charles Dundas KIA - hit by Me 109 fire somewhere near Isle of Wight, probably south.
Suitable claims: Gefr. Friedrich Schumann (1.) z 1./JG 2, Spitfire at 17.15 Isle of Wight, Fw. Karl Pfeiffer (2., 3.) from 3./JG 2, 2xSpitfire at 17.20 and 17.21 S. Isle of Wight (OKL+JFV d.Dt.Lw. 4/I-265B až 267B), Ltn. Julius Meimberg (8.) from 4./JG 2, Spitfire at 17.20 S. Isle of Wight (OKL+JFV d.Dt.Lw. 4/I-104B).