Hello!
My working theory about the number "17" on the Ju 87 G spat is following:
Cirkus Rudel was commanded to Baltic Front in July 1944 and returned back to Hungary in August 1944. Finnish liaison officer in Luftflotte 1 mentions about the unit and IIRC it consisted of 32 Ju 87s of which only three were "Kanonenvogels".
From the data at
http://www.ww2.dk/air/attack/sg2.htm (Michael Holm's site) I have interepreted that the Rudel Commando was in essence III/SG 2. Interesting is that after returning to Hungary III/SG 2 tranfers the remaining Ju 87Gs (all two) to another unit. This another unit most likely is 10.(Pz)/SG 2.
My guess is that the two new planes got running numbers from 10.(Pz)/SG 2. Allocation perhaps taking place already during July - 10th Staffel starts the month with 9 Ju 87D and 6 Ju 87 G so next running numbers would have been 16 and 17. The codes may have been (and remained) as those of III Gruppe Stab ( T6+_D) as they are in the photo.
IIRC on the background on the other photo is flying T6+FD (16?) as pair. Personally I would be much more interested in this pilot&plane (as it is "non-Rudel"). Especially the Stammkennzeichen. Thank You CJE for the photos.
Just my two (Euro)cents,
Kari