Razer blade 1080p upscaled to 4k when connecting to a 4k external display

So, i was out at a friend's house, and i tried to connect my razer blade 1080p to his 4k tv to play some games. Duplicate displays. But then my blade's display became 4k.

I know it's not possible to change resolutions, just wanna ask if keeping it to duplicate display, will harm my laptop's monitor.

And also will only displaying to external tv, save me some battery.