Since Albrecht was a Platinum Rank Adventurer, and he explicitly told them that he was going to register Sheila into the guild, there was nothing the guards could do. They had to let him in, otherwise, they might incur the Platinum Rank's wrath on them.
What they did was already way below the line, but they knew that they'd be pushing Albrecht over the edge if they were to continue pissing him off.
Still, they couldn't believe that both tags that Albrecht used were actually legitimate. Usually, once someone moved up in ranks, their lower-rank tags would be deactivated. Some throw them away, while the majority keeps them as a memento to remind them of their past self.
It didn't even occur to them that all Hereos has two tags. Then again, they only use their Platinum Tags since it was easier to go around with it.
