From the looks of the pixelated look of the line art in the drawing. It looks like it was either 1) Drawn in Paint or 2) Drawn with a pencil tool in something like Photoshop (In which case, wouldn't you need a tablet?). Of course it could have been drawn, scanned in, and given an effect in a picture edditing program. But how do you expct someone to think that you drew it EXACTLY the same on both sides, and if given an effect to make it look like the pencil tool, have it look EXACTLY the same, pixel by pixel.
It's literally impossible to draw something perfectly the same as an original. Unless you tracd it pixel by pixel in Photoshop, which would be pointless if you ask me.