I can install 9018 printer via USB with HP Smart successfully, however scanning does not work. However when I add HP 7500 printer via another USB, 9018 stops being recognized on USB (not there). I have used printui.exe /s, deleted all HP files and uninstalled/deleted all printers for a fresh install with no success.
I solved the problem. I could not reinstall software drivers until I deleted all registry entries for the HP printers and rebooted. I reinstalled full software driver packages for both. Now both are independently connected thru separate USB ports and 7500 prints tabloid pages,