EDIT: I should also add, that I created my own back when charcoal was first being discussed and use that for myself. Only mine doesn't add another item to the game, it just changes wood into the coal item. So all I did was add a craft recipe. I never posted it because others had made charcoal mods.
The easiest answer to that is the backstory of my mod: A while ago I looked for a charcoal mod and found none. upon discovering this, I made my own. Today, I released it so that others could find a charcoal mod when they look. I am glad that there are more out there, since charcoal works very well.
It's not a problem having more than one mod that does the same thing. People looking to code their own mods can look at them and see the differences and learn how to code a simple mod for themselves. Besides, sometimes mods are so old that they just no longer work so having different versions of the same mod makes it more likely you will find one that is currently working.