several (nearly) identical missions on offer (intended?) about naev HOT 1 OPEN

What's likely happening is that there are few potential targets for patrols or convoy escorting. So if it generates a patrol mission, it may only have 1 potential "valid" patrol route. Since the patrol missions are independent of each other, you'll get multiple patrol missions being generated exactly the same. I agree this is an issue, but the solution is a bit tricky, as we need to somehow have the missions understand the other generated missions and try to minimize overlap.

Possible solutions I can think of:

1. Extend the claim API to allow more fine-grained overlap detection so that you can have patrol missions not generate overlapping with each other.
2. Use the cache system to manage overlapping mission stuff to an extent. Would be a bit tricky, but should be possible with a high priority helper event to set up the cache (or just use some sort of spob-based indexing).
3. Relax the requirements for missions more so it is less likely that they overlap.

from naev.