As for Duttmann' s claims... quite a number of those were researched by Ivan Lavrinenko:
https://www.proza.ru/2016/07/07/1127
25. 29.12.1943 12:50 P-39 - overclaim
26. 03.01.1944 08:17 P-39 - overclaim
27. 03.01.1944 08:25 P-39 -
possible, LaGG-3 of 249 IAP, k-t Osman Ziyadinov MIA
28. 15.01.1944 07:21 Il-2 m.H. - overclaim
29. 17.01.1944 06:41 Il-2 m.H. - overclaim
30. 21.01.1944 11:41 P-40 -
LaGG-3 of 88 IAP, m. l-t Dmitry Shulzhenko or m. l-t. Petr Cherepnin, both KIA
31. 10.02.1944 09:25 Jak-1 -
possible, 6 GIAP or 25 IAP
32. 10.02.1944 12:00 LaGG-3 - overclaim
33. 12.02.1944 08:52 Jak-1 -
possible, LaGG-3 of 805 IAP or 25 IAP
34. 13.02.1944 07:48 P-39 -
P-39 of 66 IAP, lt. Nikolay Sobolev WIA, crashlanded, a/c wright off
35. 13.02.1944 15:07 P-39 - overclaim
36. 14.02.1944 11:27 P-39 -
possible, P-39 of 57 GIAP, m. lt. Ivan Shcherbak MIA
37. 26.02.1944 12:24 P-40 -
P-40 of 83 GIAP, damaged, crashlanded
38. 01.03.1944 08:03 P-40 -
possible, Yak-7b of 84 GIAP, damaged, m. lt. Zorin WIA
39. 02.03.1944 09:55 Jak-1 -
possible, Yak-1 of 42 GIAP, damaged, st. lt. Zaytsev OK
40. 11.03.1944 16:22 Jak-1 -
unclear but possible
41. 12.03.1944 07:45 P-40F - overclaim
42. 12.03.1944 07:52 P-40F - overclaim
43. 13.03.1944 08:35 Il-2 -
possible, Il-2 of 8 GShAP or 47 ShAP
44. 14.03.1944 13:00 LaGG-3 -
LaGG-3 of 249 IAP, st. lt. Petr Shcheblykin WIA
45. 16.03.1944 10:10 Il-2 -
Il-2 of 7 GShAP, k-n Vladimir Demidov and st-na Vasily Poplavsky both WIA, Poplavsky DOW
46. 16.03.1944 10:11 Il-2 - overclaim
47. 16.03.1944 10:12 Il-2 - overclaim
48. 16.03.1944 10:13 P-40 - overclaim
49. 17.03.1944 09:15 LaGG-3 - overclaim
50. 17.03.1944 09:20 LaGG-3 - overclaim
51. 17.03.1944 09:21 LaGG-3 - overclaim
52. 17.03.1944 09:23 Il-2 - overclaim
53. 26.03.1944 09:23 Jak-1 -
possible, Yak-9 of 15 IAP, m. lt. Ivan Dmitriyev MIA
54. 26.03.1944 16:07 Jak-1 -
possible, Yak-9 of 274 IAP, m-r Nikolay Volchkov KIA
55. 26.03.1944 16:08 Jak-1 - overclaim
56. 05.04.1944 13:11 LaGG-5 - overclaim
57. 05.04.1944 17:26 Il-2 -
possible, Il-2 of 210 ShAP, damaged, later repaired
58. 05.04.1944 17:30 P-40F - overclaim
59. 05.04.1944 17:31 P-40F - overclaim
...
61. 09.04.1944 10:09 Il-2 -
possible
62. 09.04.1944 10:12 Il-2 - overclaim
In total:
5 confirmed,
12 possible, 20 overclaims
Regards,
Maksim