1 tc The consonants of the Hebrew text of this verse are similar to the consonants in v. 19. The LXX has a much longer reading: “Like vinegar is bad for a wound, so a pain that afflicts the body afflicts the heart. Like a moth in a garment, and a worm in wood, so the pain of a man wounds the heart” (NRSV follows much of the LXX reading; NAB follows only the second sentence of the LXX reading). The idea that v. 20 is a dittogram is not very convincing; and the Greek version is too far removed to be of help in the matter.
2 tn The second simile mentions pouring vinegar on soda. The LXX has “scab,” but that does not fit as a sensitive thing. The reference is to sodium carbonate (natural in Egypt) which can be neutralized with vinegar.