If you want to understand the reasons behind this requirement I highly recommend reading the design paper: Duplicacy paper accepted by IEEE Transactions on Cloud Computing
Either way, it’s always best to read and follow the manual of the tool you are using, especially when data consistency is at a stake.
It is not “vs”. It’s cats vs pizzas.
You see, it’s much better to use a fork to eat steak and use a spoon for ice cream. You can, of course, eat steak with a spoon albeit with a lot of struggle and the same goes for a fork with ice cream. You can also use a single tool like a spork for both to make both experiences equally mediocre. But why?
You have two distinct use cases:
- Keep one or more folders on one machine in sync with one or more folders on the other machine
- Backup data from both machines.
These two use cases are not related to each other in any way, I’m not sure why are you imposing an arbitrary restriction of accomplishing both of these unrelated tasks with one tool.
For data sync, there are many tools and approaches available: from point-to-point Resilio to rclone mount with crypt via cloud storage at OneDrive.
For backup, you have duplicacy, that supports backup of multiple clients to the same storage thereby saving space at the target due to deduplication.