by DNAmers
Ah-ha! Of course, that'll be it.All five 'extra' tiles do indeed have differing costs on each side. Still, this doesn't explain why I'd have two (incorrect) copies of Sentient Hull and Distortion Shield, when the game only calls of one of each ...
... still, no matter. I've one of each with correct costs on both sides, and one is all I need. Even if I may have been secretly hoping for a legal second copy of Point Defense.
Thanks again, folks. :)