multiple villagers claim the same jobsite block

My unemployed villagers constantly claim jobsite blocks that are already claimed. The original owner of the jobsite block then doesn't have access to it anymore. I have to break the jobsite block and replace it, and I should not lose the progress i had with the original owner, but it seems to be a game of chance wether I can keep my progress or not. This is really getting on my nerves. And blocking their path to the jobsite block doesnt help either.