Once by <DESTRUCTION> of the defender that was captured, and a second time by <DEFLECTION> of the defender that recaptures. So whatever threat was being met by these two defenders has lost -two- defenders, not just one.

In other words, A and B meet the threat to C but A also meets the threat to B. If B is captured forcing A to recapture, then B no longer meets the threat to C because it is "back in the box" while A -also- no longer meets the threat to C because it has been deflected to recapture for B. Thus the capture of B and the recapture by A has removed two defensive pieces that were meeting the threat to C, not just one.

See 26 ... ♕x♖f3!! below, which <DESTROYS> the White f3-rook defending the h3-forking square and the 27 ♗g2xf3 <DEFLECTS> the White g2-bishop which was defending the h3-forking square.

Event "ICC 3 0"
Site "Internet Chess Club"
Date "2006.07.23"
Round "-"
White "BANJOVI"
Black "Avekh"
Result "0-1"
ICCResult "White resigns"
WhiteElo "3273"
BlackElo "3368"
Opening "Alekhine's defense: Maróczy variation" ECO "B02"
NIC "AL.10"
Time "18:30:22"
TimeControl "180+0"

1. e4 Nf6 2. d3 Nc6 3. f4 g6 4. Nf3 Bg7 5. g3 O-O 6. Bg2 d6 7. O-O Bg4 8. h3 Bxf3 9. Qxf3 Nd4 10. Qf2 c5 11. c3 Nc6 12. g4 Rc8 13. Nd2 b5 14. Nf3 b4 15. Bd2 bxc3 16. bxc3 Qa5 17. Qh4 Qa6 18. f5 Qxd3 19. Bh6 Ne5 20. Bxg7 Kxg7 21. Nxe5 dxe5 22. g5 Nh5 23. f6+ exf6 24. gxf6+ Kh8 25. Qg5 Nf4 26. Rf3 Qxf3 White resigns 0-1