Fan and flip the paper and or replace the pickup roller.
If option one works, the issue is the room or area the printers are in, it would (at a guess) be a carpeted room vs tiled, or humidity change.
On our Phaser 3635 - it is picking up 1 or 2 blank pages in addition to the printed page almost every time we print.
This is the same paper we use in a 4260 printer and that one never does this.
Any suggestions greatly appreciated. Thank you.