App icon duplicated, with a 'grayish' overlay.. iPhone6 - ios8

So, I've got this iPhone6 since a week now. Today my WhatsApp duplicated itself with a 'grayish' overlay on it. I can move it around, but when tapping it nothing happens.

How does this happen and how can i get rid of this? I guess it might have happened after an update, second time this happened. First time it happened a different app duplicated itself just like this.

I've been searching the internet, but could not find any explanation/solution. Hope you guys can help me out!

Thanks in advance!

Down here i made a screenshot of it.