Derelict freighter quest no longer random.

I'm having an strange problem with my derelict freighter missions. I'm getting the same quest over and over. What I mean by that is the credentials are ALWAYS from "Security Officer Lengfa", the captain's log is ALWAYS the same story, and the freighter is ALWAYS infested with biological horrors. The only thing that changes is the layout and number of rooms. And no, I'm not using the emergency receivers in the same system. I'm definitely moving around my local "star neighborhood". In the spirit of exploration, I never use a receiver in any system twice. I even try uncharted systems.

This started when I got tired of getting receivers one at a time from Helios and just bought 19 of them (the exact number I needed to finish maxing my slots) from the scrap dealer in my home system. Before I did this, the derelicts I would get were truly random. Now, I've used 7 of the 19 and it's always the same.

If you get these from the same place like I did, does that make the same derelict spawn? Up until now I thought it only mattered what system you used a receiver in. I'm getting really tired of fighting roaches and glowing nutsacks. I've actually started to miss turrets and rouge AIs.