As stated by whibr the only way to do that is to add a Machine name prefix to the writable. Theoretically you could create a much writables for a user as you would like to as long as the prefix is different all the times, otherwise it won't create it because it says the file already exists.

You could also disable the writable while testing, might be an option?

And yes, writables are both heaven and hell, it takes quite a lot of work to maintain them, I really depends on your use case to be honest. I think you should not give a writable to anyone (although that's what were doing ). For developers it is very very nice. Or for classes in which students must be able to install software for a specific class..