Here are the steps I followed to install Duplicati on a Ubuntu 16.04 system:
sudo apt-get update
sudo apt-get install mono-devel
wget https://updates.duplicati.com/beta/duplicati_2.0.3.3-1_all.deb
sudo dpkg -i duplicati_2.0.3.3-1_all.deb
sudo apt-get install -fY
sudo dpkg -i duplicati_2.0.3.3-1_all.deb
sudo systemctl enable duplicati.service
sudo systemctl start duplicati.service
It took me a while to Google this information to get it right, so hopefully this will make someones life simpler, if that’s you please comment below or share this post.