Sorry empty replied, I'll edit this in reply in a sec
The client seed is just one part of the hmac algorithm that generates the hash the float/roll is based off of.
It's the first part of the message, think the lock. The shape of the keyhole... it's kind of irrelevant, as long as the lock works. But that's even kind of a bad analogy by itself.
When you take all the components,
hmac(serverSeed, clientSeed:nonce:round) = outputhash
it is the outputhash that matters, specifically the first few bytes of it (for some games, more for others), and there is no way to predict how that outputhash is going to generate off of only a single part of the hmac build. That's why it's kind of fruitless.. it's the only thing we can control, but really, you don't control the actually important part, which is the encryption itself.
Luckily, that does mean that they also do not get to control the entire hmac construction, we get to pick one element of it before it's committed... that's the point. It's not about what the client seed is or isn't capable of, it's not capable of anything on its own, and only considering it as an overly important element is wasteful.
Unless the server seed is the same, which it won't be, the games will always end up different, even using the same client seed. You need all parts of it to be the same to resolve the same bet.