contract drawings are implied copyrights that the architects own, unless the contract specifically states that the owner has the right to duplicate said drawings x number of times. at least that's my understanding.

betadine is correct.

The problem though, in practice, is that the client would need only to change the decoration by a small amount to make it a "different" design and then use it.
There has been at least one case in which a client took an architect's plan, did nothing more to change it than "mirror" it (flip it backwards or left to right) and then built it. The architect sued, and the court found that this was enough of a change that it did not find a copyright violation!
Particularly in a situation like this, in which some other professional has been hired to complete the drawings for use in the later restaurants, there would only need to be some small changes made to establish this as an entirely different design.

beyond just changing the design a little, it's also potentially very costly for the architect to sue to recover the lost work. unless you (and your lawyer) have a very tight contract and very tight case for breach of copyright, many unscrupulous owners will go ahead and dare you to sue.

my experience is that owners for 'repeatable' type work typically think that they automatically own the rights to reproduce the work many times over. some that i've dealt with genuinely didn't understand that they didn't own the copyrights to the design and have subsequently tried to get that into the contract (one prior to the work, one after).

Thanks a lot

But i think it sucks that client can do this kind of things

We ( the company i work) already are in something similar, but without contract , just design ideas throup during a meeting , so even less opt to sue

Thanks a lot

This is an element to our business we need to get a hold on. A contract with a client that specifically states that any design that uses your design as a basis to create a likeness that therefore is theft. Without permission is subject to prosecution. We cannot allow ourselves to be taken advantage of. Read disclaimers on Photographers work and the work of the film industry and the software industry . If you put something writing and they agreed to it should be legal grounds to sue if they violate that contract. I've had clients take my design work to other architects and they put my design on their title sheet and continue working with that client. Thats when I started feeling violated a began looking into this issue. We all know that people can get away with this stuff but rarely do anything about it. People that I have talk to outside this industry think I'm being childish about it. Personally I don't like being taken advantage of.