One note, two stems

[Megan]

What is the reason for two stems in a note , how should it be played?

[Chris]

The two stems are just an indication that there are two separate voices going on, as you can see on the next beat, where there are two different notes being played. It just so happens that both voices are on the same pitch here. Think of a four-part hymn, which is often written on two staves, like piano, with the soprano and alto lines on the top staff and the tenor and bass lines on the bottom staff. The upper parts, soprano and tenor, will be written with all the stems up, while the lower parts, alto and bass, will be written with all the stems down. This makes it easy to distinguish one part from the other.

So if a note has two stems, you don't play it any differently, but it lets you know that it belongs to two separate parts, and you should work it into the melodic flow of both.

[Megan]

Many thanks for the explanation Chris.
I shall try to commit it to memory.
The theory of music is fascinating the more I read.