Shooting arrows with sword bug? (1.10.2)

So. I found this strange bug and it really didn't make sense to me but I think it might be a duplication glitch. So what I did was put a bow in the first slot and a diamond sword (Works for any sword) in the ninth slot. So I first went to my first slot before I went into the Inventory GUI. I pressed the 1 Key while hovering over the bow. I had the diamond sword but for some odd reason, it glitched and it can shoot arrows just like a normal bow. I'm not sure if this is client sided or not but I could shoot from both the sword and the bow so it might be abused as a duplication glitch. And how you do the duplication glitch is do the same thing except when you could shoot arrows, you drop the item and now you have 2 bows. Duplication glitch. Anyways, thanks as always!