not to mention most of the keys have 3 strings so chords sound in tune due to physical/harmonic factories involved with those but that's a different story)
It is a simple question, E0 or not E0 is the question How low will the tuner be accurate? 20.602 Hz? No?
There is also another reason for multiple strings...
For a 3 note major chord to be perfectly in tune... sound right on- dead in tune...
The third has to be SLIGHTLY and i mean very slightly sharp