Duplicate informations on 2 screens

I'm french and I work on a project since some times and now my first phase is finished (control of temperature on 24h with day temperature different of night temperature and this variation is different for the seasons which are declared with progressive evolution ; control with the same idea of light). I use a display TFT 1.8" with Adafruit library ST7735 for the moment but I would light to know if it is possible to duplicate this on an other screen, perhaps more large (?), to have informations in an other place than where is the ATmega2560. This without have a ATmega which would come slow for reaction/calculs.

So the question is : is it possible and can you help me in this work ?

Thanks a lot

You told us the library and display size but you need to be more specific. You need to post a link to the
vendor of the display you are using or documentation that gives connection and interface information.
Since you already have it working you obviously have the information we need . Now all you have to do
is post it.
What are connections.
Post the code using the "#" code button to create a scrolling window.
I don't know if it is a shield that plugs directly into an arduino or uses a cable interface but likely it is a SPI
interface which is Chip Select based, rather than address based so there should be no limit to how many
displays you can run at the same time other than processor overhead sending the information which I
don't think is an issue. You should be able to pick a SPI display and use a different arduino pin for a chip
select .
I have no experience with TFTs so someone else will have to help you with that but if I were you I would
not buy a larger display until I had all the documentation and libraries needed to make it work, but that's
just me.