Some games' core concepts require the same level but different concepts, or "modes". Due to an abundance of actors, I believe one could create a level "template", copy and paste it, and therefore simplify the process of modifying the next level accordingly. Remember, same level, but different modes.
Let's take Call of Duty into example. I'm not a big fan of it, but if I remember correctly, one of the Call of Duty's have multi-player maps from the campaign. If I am guessing correctly... they probably created the campaign's map first. For whatever reason, someone decided, "Hey, let's take a part of this map from the campaign level and use it for multiplayer!" And so they did. What is the moral of this story? Well, technically, since they created the campaign's level first, they had to copy and paste it to another level "slot" (I'm not familiar with hardcore programming) for the multi-player map. Consequently, they took the action to delete the campaign's opening cut-scene, the enemy AI, etc. Thus, the multi-player map would not be the exact same if they could not copy and paste to begin with. If they re-built from scratch, it is likely that there would be slight and/or major differences. They would also have to re-add the level's aspects, such as lighting, perhaps permanent texture decals, all of the tedious things.
My point is that it would be easier just to be able to copy and paste a level as templates to reduce the process of taking the tedious actions. Yes of course, even if this feature could not be implemented, the level technically does not NEED to look the exact same. However, having the level to look the exact same is a convenience and even a necessity for some videogames. Redesigning the level to be the exact same may be too time consuming for some people.
Also, I saw no option to delete levels? I mean if a level and it's actors are really pissing me off, I usually find it easier to delete everything and start over.
Throw in the input