How many persons did John see sitting on the throne in heaven?

Note: The correct answer depends on which passage we are referring to.

ONE throne is mentioned in (Revelation 4:2) which is in reference to the Lord God Almighty (Rev 4:8). However, there are TWO thrones mentioned in (Rev 3:21),  “To him that overcometh will I grant to sit with me in my throne, even as I also overcame, and am set down with my Father in his throne.” 

The answer is self-explanatory when we read it for ourselves.