Do they have to be absolutely 1000% identical? I have plenty that are similar, sightly different, but they function exactly the same way for the same size webbing. I'm amazed a covermaker can't sort this out, unless the problem is that you need a 1000% identical match
It does not need to be 100% identical but it must be as fixed and strong as the current ones.
My local covermaker have another type that he thinks works as well but I have found that they loosen themselves in a way that the original does not.