I know players are being compensated for Signature Lor'themar Theron and Grand Magister Rommath but is there anything that can be done about opening legendaries you already owned the signature of while still missing legendaries from the set, or in this case standard rogue legendaries? I opened a normal Putricide from a standard rogue pack despite already having the signature and not having all the current standard rogue legendaries. Do signature cards not count as "collected" when it comes to duplicate protection or something?
Signatures have a weird way their duplicate protection is handled. Instead of not being able to be opened from packs if you own the card already, they can. To compensate, you're given the option to reroll your old dustable Legendary into another one from the same set, which does obey duplicate protection.
Hmm, those weren't nerfed, so maybe you didn't have them. You could check the rogue collection progress for Barrens, Stormwind and AV expansions. When you have the rogue collection achievement, then you had all those cards at once at some point (it doesn't count if you dusted one before collected the rest though, so 12/13 wouldn't tell us much).
But yeah, the class packs could also just be bugged and not respect duplicate protection.