Yes. High speed copiers use high voltage discharges. You can smell the ozone they create in a small room. These discharges collect dust and the copier has to be cleaned periodically. Anthrax spores behave just like tiny particles of dust.
This sounds like the most logical explanation for the discovery on every machine. Paper, wrapped in the ream covers, from the paper mill, is about as close to a sterile substance as can be found outside of a medical setting. I don't think it went from machine to machine, but rather was collected from the air by the static charge. How long was the building in use before it was shut down? Probably plenty of time for the anthrax to be minutely in the air all through the building.