I haven’t been able to recreate this reliably and nor do I have screenshots unfortunately (it was 2am, bite me :P) but I came across an odd bug last night when all the merchants inside our Garrison (Blackgate desert borderlands) became siege merchants rather than selling what they were supposed to (Outfitter and Mystic Forge NPCs). Merchants in spawn were still selling the right items just fine, but those in Garrison only showed siege blueprints.
Expac sucks for WvW players. Asura master race
Beastgate | Faerie Law
Currently residing on SBI