This is a nice find. Timner's Ellingtonia (5th ed.) shows nothing between June 8 and July 6, 1946.
Here is the personnel of Ellington's July 9, 1946 record date for reference:
Taft Jordan, Shelton Hemphill, Cat Anderson, Francis Williams, Shorty Baker (tp),
Ray Nance (tp, vln, vcl) Joe Nanton, Lawrence Brown, Claude Jones, Wilbur DeParis (tb), Jimmy Hamilton (cl, ts) Johnny Hodges (as) Russell Procope (as, cl) Al Sears (ts), Harry Carney (bar, b-cl, cl) Duke Ellington (p), Fred Guy (g), Oscar Pettiford (b), Sonny Greer (d), Kay Davis, Al Hibbler (vcl)
The contents of the uploaded music files, each of which is about 15 1/2 minutes, appear to be the following :
1. Take The “A” Train/Announcement/Take The “A” Train/Transblucency (kd vcl)/
C Jam Blues/I’m Just A Lucky So-and-So (ah vcl)/Announcement/
Riff Staccato (cut off)
2. Riff Staccato (cut in)/Come Rain Or Come Shine (kd vcl)/Blue Skies/
Things Ain’t What They Used To Be/Outro/Intro Of Interview/
Start Of Interview
Thanks very much. Any other acetates lying around?