Hopefully someone will PM you with a copy. In fact PM me and I'll send you what I have. Of course, without being compressed passing through different platforms, you run the risk of the application losing attributes System 7 needs in order to run it. Another option for you is to set up something like Basilisk II on your Linux machine and run a virtual Classic Mac. That way you can run a later OS with more options for expanding Mac software. Often new archive compression schemes are incompatible with software which runs under System 7, though most of the vintage software is compressed under a native OS application.
The Duo line was one of the greatest products Apple ever developed. Unfortunately it did not impress the average consumer, probably because all of the extras began to add up and weigh the average traveler down, because as you discovered, without a dock of some sort, the Duo is practically useless (not to mention having the appropriate software on hand). I wish Apple would re-visit this technology, but it goes against their marketing model (one computer for each location), particularly now that they have the network "Cloud". Today's technology would make a modern Duo an incredibly practical device.