You can handle cases like this easily by raising a moderator flag. Click on the "flag" icon below the problematic post, click the "other" button, and type in a description of your concerns like you've done here. For example, include the link to the duplicated answer over on Ask Ubuntu.
Moderators have tools to investigate and deal with problems like this. Depending on what is appropriate in the specific case, they may either delete the plagiarized post or destroy the entire account.
This way, if your concerns were wrong (not that they were here—this is pretty clear-cut), you don't risk humiliating either of the parties publicly.
I don't believe there is a blanket policy banning bots. If you can write a bot that generates relevant, useful content, then we have succeeded. That said, there are still two problems:
If there is cross-voting between a bot and its owner, this is a problem. Moderators can investigate this (although they can't see individual votes, the system shows them clear patterns of abuse), and they will issue the appropriate warnings/bans once they become aware of it.
Plagiarizing content from other places is completely unacceptable. Giving attribution would be a minimum requirement to not have the answer immediately deleted. But even so, a user that posts nothing but other people's content, whether attributed or not, would not be looked favorably upon. I'd say this would have to be handled on a case-by-case basis, but in general, it would not be allowed. Moreover, it is very unlikely that the copy-pasted content will be relevant in other contexts.
It is an interesting question, though. What if I wrote a bot that translated answers from the English language version of Stack Overflow to, say, Portuguese, and then posted these answers (with proper attribution to their original English authors) to parallel questions on https://pt.stackoverflow.com/? I'm not sure what the policy would be on that. I imagine that the moderators and community managers would have to have a chat amongst themselves before an email showed up in my inbox. Something to try on a rainy day. :-)