Seeing double!

Conditions on 15m and 12m are quite good at the moment.  It's slightly windy today, so I turned my antenna into the southerly wind, and listened to what was going on in that direction.

5T5PA was busy at it again, with a very strong signal.

5T5PA, split in two...

But, I wonder if you have any explanation, dear reader, for the double signal, which continued for as long as I was listening - about 10 minutes?  It doesn't look like a propagation effect, as both signals are identical in characteristic.  I'm assuming it's some kind of software issue at the transmitting end, but not one I've ever seen before. [UPDATE: see comments, below, for the explanation]

Looking at general reception reports, I was amazed to see EA8BFK reporting me at +24dB!  That's probably the strongest report I've ever seen.

Incredible signal to the south!