Double tracking is normally used to thicken up a guitar sound.
If you are happy with the way it sounds Id not bother.

Spatial separation can be used to several ends. I usually use it to stop tracks that have a similar frequency distribution from fighting with one another. This is why people often pan one guitar hard left and one hard right and then only adjust the EQ a little bit as opposed to having them on top of one another and having to EQ them to bits.

Their is a ADT (automatic double tracking) function which will look at the tempo of the song to determines the delay added to the second (copied) track. This avoids a phaser-ish sound and can work well.