During the process of translating a literary work, it is possible that we come across a bit of text which does not belong to the work as it is.
We may meet epigraphs, for example. Epigraphs are short quotations which have been put at the beginning of chapters, and which belong to another work. Even though they (may) appear in the same language as the literary work, it is likely that they are translations themselves, translated from another language.
So, what can be done in this case?
Some translators translate roughly from the translated and think that this is okay.
It is not.
This bit is not equivalent to the rest of the text.
This bit belongs to another literary work, and we have to deal with it as such.
First we have to do some research in order to identify the work from which it has been taken.
For example, this bit could be an extract from the Bible.
In this case, we have to go to the Bible’s official translation, find the relevant bit, and insert it into the target text. In order to avoid endless translator’s notes that may disrupt the reader, we can cite the source in the work’s introduction.
Or, this bit could be an extract from a classic work such as the Iliad. In this case, we can use any published translation we think that fits the style of the text we are translating. Again, in order to avoid endless translator’s notes we can cite the source in the work’s introduction.
Bear in mind that it won’t be such a good idea to try your hand at translating this bit yourself!
When we translate a work from a language into another, such problems come up very often. So, since translation demands from us to re-create the work into another language, before getting down to the actual translation work it is imperative that we 'unlock' the source text. Keep in mind that processes such as literary allusion and intertextuality can transfer significant tension from the source text to the target text. Therefore we must be ready to move between texts the way we move between languages, keeping at the same time our eyes open in order to avoid traps as the above.
Have you ever met a bit of text that was itself a translation? What did you do?