that's very odd
World Team 2013: How can Khenin miss such an obvious and good move? Pls explain

I have a feeling that the game-score (the moves) were reported incorrectly. Here is a quote from the official report on the Chessdom web-site:
" As for Ivanchuk, he punished Khenkin for playing a little bit tame and won in a very clean and technical way."
... no mention of a bizarre double-blunder.
Perhaps the moves actually played in the game were:
15. Nd3 Nb4 16. Nxb4 Nxf4 17. exf4 Bxb4

I have a feeling that the game-score (the moves) were reported incorrectly. Here is a quote from the official report on the Chessdom web-site:
" As for Ivanchuk, he punished Khenkin for playing a little bit tame and won in a very clean and technical way."
... no mention of a bizarre double-blunder.
Perhaps the moves actually played in the game were:
15. Nd3 Nb4 16. Nxb4 Nxf4 17. exf4 Bxb4
maybe.
I got PGN from official FIDE website.
On move 16 why didn't he move 16. Nxe7+?
He just blundered away the game.
Here is the game: