For some reason, they came out with another "remastered" version of these two CDs with different covers (see here:http://www.disquesdreyfus.com/catalogue/538422392-ko-ko.html) , and the sound is weird. From what I remember, the originals were indeed good.
Here is a track from the "remastered" version (but with the original cover), that I found on YouTube:
The albums are on the Internet Archive, with the liner notes, and some sound excerpts:
https://archive.org/details/lp_duke-ellington-1940_duke-ellington
The sound seems to be quite good (samples are vinyl rips).
And here is another Smithsonian version packaged as a box set: https://archive.org/details/lp_an-explosion-of-genius-1938-1940_duke-ellington