I have done a medical editing project for a very picky client lately. They had two translators translated the English into traditional Chinese, and asked me to mix-edit the two versions of translation to a perfect one. Then they asked a doctor from Taiwan to check the translation to make some revisions and sent back to me to put those revisions to the files. This is not it, then they back translated the translation into English again to compare it with the original English version.
Personally, I think that’s a bad idea to do translation like that. It wastes a lot of time and energy to do all the back translation and comparison. And the comparison was done by the client who knows nothing about Chinese or translation. We know that translation is a very subjective job, you can either translate it this way or that way as long as it does not change the meaning of the original sentence. The back translation can be very different from the original article due to the different ways of expressing tense, singular and plural noun between English and traditional Chinese.
But still, sometimes you can find mistake by this way. Here is the example:
Original text: Rate total improvement whether or not in your judgement it is due entirely to drug treatment.
The original translation: 請根據您的判斷評價整體改善度，標明完全因藥物治療而獲得的改善。
Back translation: Please evaluate the degree of overall improvement based on your judgment, and indicate the improvement obtained completely as a result of medicinal treatment.
Note from the client: This does not match the meaning of the original English, which means that, regardless of the clinician’s perspective on whether it was caused by the study drug or outside factors, they should rate the improvement.
After I recheck the text, I found we made a mistake. I retranslated it as the following: 無論您認為改善是否完全基於藥物治療獲得，都請評價整體改善度。
So if it is a strict translation and the client does not care about the cost, they can consider doing translation this way. For some very crucial documents (especially medical ones), we have to be careful on every single sentence. Only by this way can we improve our translation quality.