Sorry but, no is not safe. You shouldn't do that. If you do pre-printed pages on any color Xerox printer and then put on other mono laser just to print black, you will experience a kind of ghosting, i.e. some toner printed on the first printer will be stuck in the fuser of the second printer because you are melting again the first print.
Small mono printers like HP uses too mach heat in the fuser.
If you use ink jet technology to print the black, is OK!
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