Iron and ice, bug or normal?

Somehow, this person is switching between cannon and archer tower. Is this a normal update that i didn’t know about or is this a bug/hack? Can anyone pls clarify this for me? @staff ? (Oh yea and umm when we summon at the same time its like a this visual glitch. Can you fix it too pls?)

You can switch towers by building another tower of a different type on the original tower, and it won’t downgrade the level. This is very useful; an example of how one might use it is switching away from cannon when there are flying units present.

Edit: clarity


OK thx for the info. When did this become a feature tho? Was it posted in another topic?