Interesting Heads up hand

Full Tilt No-Limit Hold'em, $0.50 BB (2 handed) - Full-Tilt Hand Converter from HandHistoryConverter.com

SB ($52.10)
Hero (Button) ($47.75)

Preflop: Hero is Button with ,
Hero bets $1.50, SB raises to $5, Hero calls $3.50

Flop: ($10) , , (2 players)
SB bets $7, Hero raises to $14, SB calls $7

Turn: ($38) (2 players)
SB checks, Hero checks

River: ($38) (2 players)
SB checks, Hero bets $20, SB calls $20

Total pot: $78 | Rake: $0.50

Results:
Hero had 9, 9 (four of a kind, nines).
SB had 3, A (two pair, Aces and nines).
Outcome: Hero won $77.50