Thanks for the info @bug11. At the duplicati homepage I've seen a debian package (the same as for ubuntu too) so at least for debian jessie (OMV v3) you can use this package. Unfortunately there isn't one for Wheezy (OMV v2). So I guess you mean with docker when you use OMV2?
Edit: and is it possible to automount my amazon cloud drive with duplicati so that I can use it like an internal/local drive? And will everything crypted when I copy data to this drive?