Two signals alternately on the left and right of a frequency
That looks to me like two unrelated USB signals, with a carrier that happens to be in the middle. It could be coincidence, or perhaps this is a pilot carrier to make tuning easier. Were you able to listen to what was being said? That could be a big clue.

Here's another USB waterfall sample:



(many more good samples at source)

The asymmetrical shape, and the concentration of power at the low end, corresponding to the \$f_1\$ formants of human speech, gives it away.