i mean you don't use the same tie everyday normally, isn't it okay if she has 2 of them? just give her the fucking gift
I suspect it's more a matter of timing. Giving her a hairband right after she just bought one, with another friends encouragement, feels less special then giving her one while she's hesitating over which one to get. She's also probably worried about looking like she just copied Hana.
Now, realistically, Hime probably wouldn't view it that way and would probably appreciate the gesture for what it is, but teenagers and unfounded insecurities might as well be synonyms.