Tuned percussion question

It is not the norm for music for these instruments to be published with two staves. It is probably more common for marimba than the others because its range is actually wide enough to call for it. See for instance http://www.salazarfinetuning.com/keyboardrange.php. While there are a variety opf different models of these instruments, on average the marimba goes much lower and has a much more extensive range.