Realms bug, I was able to stack bows

When I was playing on a Survival Games server, I took 2 bows quickly and they ended up stacking up on a single inventory slot.

What I expected to happen was...:
For the 2 bows to have their own slot, like one bow on one slot, another bow on another

What actually happened was...:
The 2 bows were stackable

In the attachment below, you can see in the inventory slots that there are 2 bows stacked in one slot.