Another leaked picture confirms single camera for Samsung Galaxy S9
Alleged Samsung Galaxy S9 back cover
However, those who absolutely must own a flagship with dual rear cameras may have their preference satisfied since the Galaxy S9+ is said to feature such a camera configuration.
Samsung is expected to officially introduce the Galaxy S9 and S9+ in late February, but the flagships won't be available for purchase until March. Even so, that will be quite a head start for Samsung's top-tier handsets, which will probably be the only new important flagships that will sell for several weeks maybe.
Things that are NOT allowed: