Cliff at the Shack wrote:

Heard at the Shack on the Bayou in southeast Texas:

6768 kHz AM
0400-0425, November 3, 2003 UTC

Two simultaneous female Spanish 5-character number readers
At first, the stronger one was distorted.
It could have been two stations, but it sounded more like one with two audio
streams mixed.

As an extra added bonus, there was weak CW in the background.
I could only make out occasional characters.

Probably Cuba. El Jefe's spies have been known to mix in Radio Havana
Cuba audio with the numbers.

I heard regular programming from WWCR's transmitters doing that during the
recent solar activity. I figured it was a form of selective fading, the regular
skywave mixing with the rapidly fluttering signal bouncing of the aurora. (I'm
too far from WWCR to get its groundwaves.)

Bill, K5BY