Recently I've read some fantasy novels where a princess was replaced by a look-a-like in order to marry her off to another person of royalty, because the real princess couldn't be found. Examples are Ciri in 'The Witcher' and Arya in 'A Song of Ice And Fire'. I wondered if there are any documented cases of this in actual history. I don't really have specific time period in mind, I'm more interested if it happened at all that we know of.
Sorry, we don't allow "example seeking" questions. It's not that your question was bad; it's that these kinds of questions tend to produce threads that are collections of disjointed, partial, inadequate responses. If you have a question about a specific historical event, period, or person, feel free to rewrite your question and submit it again. If you don't want to rewrite it, you might try submitting it to /r/history, /r/askhistory, or /r/tellmeafact.
For further explanation of the rule, feel free to consult this META thread.