Does the installation of same packages for two different python projects in two virtual environment result in wastage of memory?

I was working on a Django project and got a doubt that if we have two projects running in our system say P1 and P2 and both has its own venv as V1 and V2. At some point of time both project requires same python packages and I if am to install that package twice in my system result in wastage of space? If so what is the use of virtual environment? Only to run projects in isolated environments? Please can anyone tell me?