So I've attacked numerous Zirax space POIs and have not seen a Zirax Battlefleet before until now. Very scary and fun... but anyways

I don't recall which base I was attacking when I saw the base was calling for help, but I remember the message about Incoming signatures and the fleet showing up.
In no time my shields were out and I was on the run watching blocks fall off my ship.
Luckily I got out and repaired the ship. But it was intense and maybe a little much for my PC to.

Later I decided to go back to that sector and I could still see that terrifying fleet just waiting for me. I'm guessing they don't go away and must someday be dealt with? Someday...

I decided to attack a different POI in the same sector far away from the fleet (like 20km). It was Navy yard POI if I remember correctly. I took out its shields and generators, and then proceeded inside to find the core with a friend. I noticed a destroyer getting close, so I went back into my ship to deal with it while my friend continued to search for the core. And then I got the dreaded message "Incoming warp signature". It was another Battle-fleet.
And then my game crashed.
Luckily my friend was able to get into my ship and take off. Unfortunately half the ship was ripped off but recoverable and still with a functional warp drive. Later I was recovered too.

So now I'm curious, is there something special with this Zirax sector? It is around a lava planet in a K star system and says Medium difficulty, but maybe there is some other unknown factors? Or did we get incredible odds to have two Epsilon Zirax Battlefleets appear in the same sector for different POIs? Should I fear this sector and just accept the Zirax ownership?