Another one from forum member @Sarin.

Destroy the attacking pilgrim.
Dock with the wreck.
The mission/pilgrim dockscreens show followed by loot screens as expected.
Dock with the Sisters station to complete the mission.
Redock with the wreck.
The mission screens show again. They will show twice in sequence in all further dockings.

Quick testing shows mission property 'epilogueCompleted' is being reset to Nil when the player docks with the Sisters station.