It may seem hard to credit, but it can often be difficult to tell who actually owns the translation rights to a particular work – there is generally no © symbol on the inside front cover of books, for instance. This confusion arises from a confluence of several factors.
The first is the confidentiality that adheres to the publishing industry naturally, in any country. People simply do not make the information public, and it can be difficult to weasel it out of them.
Added to this is the generally fluid nature of law in China: a contract is less a legally binding document than it is an expression of how both parties hope the arrangement will develop. Publisher A may publish a certain book. Once the initial print run is sold out they may, for reasons known only to themselves, decline to print further copies. Perhaps there are clauses related to additional print runs in the contract, perhaps not; in any case, the author eventually gives up trying to talk them into printing more, or returning the copyright. Two years pass. The author meets Publisher B, they eventually agree to publish a new edition of the book. Publisher A is either unaware of the deal or has no comment. Now we set out to find who owns the world-wide translation rights: No one knows. Publisher B says they own them. Publisher A, if they can be induced to answer the phone, may or may not claim knowledge of the situation. The author will say Publisher B owns them so long as Publisher B is present in the room, but later privately confides that s/he's still got them. There is no contract at all with Publisher B. Maybe translation rights were mentioned in the original contract with Publisher A, maybe they weren't. Maybe we can't find any copies of that contract. You see the difficulty.
Finally, there's the legal ignorance (real or feigned) of the authors themselves. Many do not really know or care about the ins and outs of copyright law, and will cheerfully sign multiple contracts with multiple foreign publishers for the same rights. Or they will claim to own rights they've already relinquished to their Chinese publishers. They may genuinely not know, or they may be thinking "hey, what the hell?". Incredibly, this ignorance will sometimes be found among publishing houses, as well.
This situation is rapidly improving, but for the time being, caveat emptor.