I'm going to put in another suggestion for the Rh beads. go to heartfeltindustries.com, they have a handy calculator on their home page that will help determine how much you will need, They also offer tubes and boxes to hold them, but a lot of people simply use a small dish or two.

Once you get them charged, just watch for your humidity to drop a few points as a clue that you need to spray them with a bit more distilled water.

As for now, removing one or both humidifiers would be a good start, just keep a close eye on Rh

I would also recommend re-testing your hygrometer, just to eliminate it as the problem.