Home:Sins of A solar Empire
Features: Real Time Strategy
Gameplay: RT4X
Forum: Science Fiction Multiplayer Game
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FAQ: Multiplayer Game
Downloads: Screenshots Concept art Wallpaper Music Trailers
Lore: Epic Sci-fi Computer Game
You've got a point there! That might be why they have that caution sign. It could also be related to the docking bay itself, possibly being shorter then docks are normally regulated in that faction, which would support the idea of it being an access point for maintenance or refueling.
On another note- I think they're isn't much out of place with having multible doors. Most planes do, I think, and I've also seen it on many fictional space ships. The Great Fox being one example.