While written in Greek, this is quintessential Hebrew idiom. Let me quote a similar example directly from the Hebrew:
- Gen 2:17, 3:4, - ... dying you shall die
The highlighted phrase is just two words, both verbs, which idiomatically mean, "you will surely die".
Thus, the meaning is simple - a contrast between how the saved vs unsaved receive the messengers of the gospel as shown by some versions that uses the metaphor of an aroma/smell:
- NIV: an aroma that brings death; to the other, an aroma that brings life.
- HCSB: an aroma of death leading to death, but to others, an aroma of life leading to life.
- GNT: For those who are being lost, it is a deadly stench that kills; but for those who are being saved, it is a fragrance that brings life.
- ISV: To some people we are a deadly fragrance, while to others we are a living fragrance.
In Hebrew idiom, the repetition of the word is used for emphasis. Thus, there are not two "deaths" and two "lives", just literary style and idiom.