To the best of my knowledge, Lionel is the only one that made a repro of the 840 with dual smoke units, which were mounted in the base of the removable smokestack assembly.
FYI: Lionel also made the following changes to their reissued 840:
NO removable skylights
NO knife switches
Translucent window material added to all windows, doors, and skylights.
Interior lighting
NOTE: Smoke units could be deactivated with a strip of electrical tape across the contacts.