Should i get a second monitor?

I know its not show on the picture but i have abit of extra desk space around 30cm, should i get a second vertical monitor or is that way to overkill? (I dont mean a monitor the same size)

I know its not show on the picture but i have abit of extra desk space around 30cm, should i get a second vertical monitor or is that way to overkill? (I dont mean a monitor the same size)