Player A: 2-7o
Player B: 5-6o
Board: 4433r
Player A is currently in the lead with two pair, 7 kicker.
If the river is 8 or higher, split pot (both players play the board)
If the river is a 2 or 7, A's two pair is beaten by B's straight
If the river is a 5 or 6, B has a better two pair than A
If the river is a 3 or 4, split pot (both players play the board)
Confirmed this on CardPlayer's calculator. After the turn B has a 27.27% chance of winning, 72.73% chance of a chop.