It doesn't matter how many times she's posed nude before, or where the pictures have been printed previously - if she has certain rights to images, then she gets to make certain decisions about how and where they can be reproduced.
The irony is that most of the world wouldn't have been aware of this in the first place... but the concept of Lara in Playboy has definitely been established in people's minds, now that it's become headline news, even if that comes due to her disapproval.
The cynic in me always harbours a suspicion that these things are done for publicity. At a time when sex tapes seem to be the best way for nobodies to turn themselves into celebrities, an appearance in Playboy isn't a shocker - and it doesn't really increase a model's profile as much it used to. Until the moment you complain about it.
That said, many celebrities have experienced the surprise of seeing themselves in Playboy thanks to bought-in images, so she wouldn't be the first to be affected by the magazine deciding to act without consultation.