Funny. I was thinking about this thread in my hunt today. I was engaged with a pirate ship when not 2... but 3 other NPC ships were surrounding me.
The crew of second ship was interfering in my operation... and, oddly enough, as soon as I gave them a cannon blast, they started running away. I wanted to go after the merchant ship when my pirate prisoner was taken... but they beat it. Couldn't find them. Never saw so many active NPC ships in the same screen before. I've wrecked a few right next to each other! Driving the 2nd in to the 1st... and having a third passing the others. This picture above? Its honestly not impossible... but with maybe 2 or 3 players hunting in the same area.