Apt-cacher-ng: Is there a way to avoid duplicating /var/cache/apt?

Question

I know apt-cacher-ng is duplicating the data in /var/cache/apt. Is there a way to tell it to use /var/cache/apt, or it isn't doable due to permissions? Mi partition has little space. I could indeed make apt-cacher-ng use other partition, but it seems to me like I am wasting space. Not sure if squid-deb-proxy does the same thing, duplicating the packages. I just want it to use /var/cache/apt. If it is not doable I will understand :) Thanks!