It looks very much like the text we can read on the fuselage side is AQEU.
Since AQUE was c/n 7501 we then end up in conflict with what Miranda had to say in his vol 2 of Aviones en la Guerra civil Espanola 1936/39 where he identifies the VIVA FRANCO with c/n 7529.
The interesting fact would be when these interetsing photos were taken.
As far as I know there is no report saying that any DH.90 fled or was captured during 1938. The two reported as taken over (the already stated c/n 7501 and 7529) are said to have been taken over at the end of the war in 1939.
Since I believe only the second half of the negatives are on sale right now (I believe I have missed out on the first half), it is a bit difficult to say when Carl Schmidt arrived into Spain, but I have guesstimated this to be ca summer 1938. Since I also believe the text VIVA FRANCO was painted by a crew who wanted to escape/flee and not be shot down, at least not from the ground, they felt this to be an added security.
Now if AQEU is the true AQUE then it has to be c/n 7501 which Miranda claims was captured at Totana in April 1939 and then incapable of flight due to lack of spare parts. Well, you can probably fool me, but the negatives to me is about an aircraft taking off and then AQUE certainly was capable of flying with or without spare parts....
We cannot rule out a so called third DH.90 in Spain. In the past c/n 7556 TC-IDE has been given as the most likely one. However this cannot be since TC-IDE is known to have been handed over by the Turkish DHY to Hürkus Hara Yollari in 1954.
So how etched in stone is this third DH.90 in Spain? What evidence is there that a third one actually was delivered? I have had help from Malcolm Fillmore to check if any other DH.90 just may have been possible.
There actually is one, c/n 7552 ex F-APFK where no solid proof of capture by the Luftwaffe in 1940 exist! So again how solid is the proof of an existance of a third DH.90 in the first place??