It's called an analogy not a metaphor.
You were saying you can write 'mike' instead of mic(rophone) because Mike is short for Michael. A better (or non-faulty) analogy would be saying that you were looking at two coins instead of one and were confusing the sides
Also 'yin/yang' has nothing to do with two sides of a story. There can be unlimited sides to a story but there's only 1 correct version. Yin/yang are two opposite forces, that are always there. There is nothing in 'there's 2 sides to every story' that implies that the stories are complete opposites. And there's a correlation between yin and yang while '2 sides to every story' implies that there is no correlation between the 2 stories.
And 'good/bad' is about the same. When you say 'there's 2 sides to every story' there is nothing that implies that 1 side is bad and 1 side is good.
Both bad examples.