Hi,
I have to confirm there's no overwrite in DOTween. Its previous version, HOTween, had it, but I decided not to implement it in DOTween because the only way to have it is to use Reflection, and I wanted to avoid any of it this time (mainly for performance reasons).
Consider though that you don't need to kill a tween in order to allow an overlayed one to play: you can just pause it.
Cheers,
Daniele