After copying a world, the characters "Copy of" will pop up. When the world is copied too much times, the world character limit get broken. After attempting to type in it, it reverts to the limit.
To reproduce this bug, do this.
1. Make a world and make the name as long as it can be.
2. Copy the world
3. The world name character limit has been broken!
It probably should make that when you copied the world too much times, the world won't be able to get copied.