[Storebror]

I did a little research and both aircraft have the same Jumo 213 engine

Don't know where you got that from.
The D-9 was equipped with a Jumo 213 A-1 engine.
As for the D-13, only 2 prototypes are known to have been built, one being equipped with a Jumo 213 E and the other with a Jumo 213 F engine.
The Ultrapack 2.01 D-13 Flight Model incorporates the "F" engine on the D-13.
The "A-1" and "F" versions of the Jumo 213 differ in ways from each other as do the results of your test.

Best regards - Mike