Substitute Duffy looked certain to score when put through by Jo Kuffour's 86th-minute pass but Kuipers spread himself superbly to make a vital stop.
The visitors had skipper Adam Virgo sent off for a second bookable foul in the 44th minute but still took a 55th-minute lead through James Tunnicliffe's power header from a left-wing corner.
Kuffour equalised in the 67th minute with a low shot after substitute Andy Williams' right-wing cross.
The home side could have won it in injury time when full-back Carl Regan volleyed wide of an unguarded net after another substitute, Ben Swallow, had seen his shot blocked.
Brighton worked tirelessly to overcome their man disadvantage in the second half but Rovers will rue some excellent missed opportunities as the game ended in a draw.