Is there a way to install the latest canary version on Linux? My version shows “Duplicati - 2.0.4.5_beta_2018-11-28”
Welcome to the forum @rt1 
You can always get any release from the releases page on Github Releases · duplicati/duplicati · GitHub
They’re provided there in various formats such as .rpm and .deb
Hello @rt1 and welcome to the forum!
Linux seems a bit messier than Windows because there are sometimes many ways to install software, including possibly from a package created by the distribution. If you’re comfortable going with Duplicati’s version as suggested, and if you intend to get on canary and stay awhile, you can try Duplicati’s updater, asking in Settings to get on the canary channel. Sometimes updates need Duplicati restart to take effect.
Thanks for running canary! You can enjoy an early view of features and fixes (and help spot new issues).