NL50: 77 vs board pair and strange river bet

[AlexB182]

At first let me say sorry than I'm posting some more hands today. I'm doing some intense session review today as the last three days just sucked big style. I appreciate all your comments and thoughts very much!

Villain is 55/5/0.36 with a river AF of 4. (For those who read the AA vs double paired board thread, it's the same one. This hand happenend first.)

Full Tilt No-Limit Hold'em, $0.50 BB (9 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

Button ($49.75)
SB ($19.25)
BB ($28.10)
UTG ($52.55)
UTG+1 ($22.50)
Hero ($47.50)
MP2 ($47.85)
MP3 ($46.50)
CO ($9.30)

Preflop: Hero is MP1 with 7[img]/images/graemlins/heart.gif[/img], 7[img]/images/graemlins/spade.gif[/img].
<font color="#666666">1 fold</font>, UTG+1 calls $0.50, <font color="#CC3333">Hero raises to $1.75</font>, <font color="#666666">6 folds</font>, UTG+1 calls $1.25.

Flop: ($4.25) 6[img]/images/graemlins/diamond.gif[/img], 4[img]/images/graemlins/diamond.gif[/img], 8[img]/images/graemlins/heart.gif[/img] <font color="#0000FF">(2 players)</font>
UTG+1 checks, <font color="#CC3333">Hero bets $2.75</font>, UTG+1 calls $2.75.

Turn: ($9.75) 8[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
UTG+1 checks, Hero checks.

River: ($9.75) 4[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(2 players)</font>
<font color="#CC3333">UTG+1 bets $9.75</font>, Hero ?