Both quarterbacks missed the first meeting between the teams last month, and Darnold's status is uncertain for Sunday when the Jets visit the Bills on Sunday.
Darnold, the No. 3 overall pick of the Jets, has missed the last three games due to a sprained right foot, including a 41-10 drubbing by Buffalo on Nov. 11 in which third-stringer Matt Barkley guided the Bills to a 31-0 lead in the second quarter.
Darnold was a full participant in practice Wednesday but head coach Todd Bowles said it was too early to decide if the former USC standout would be back in the lineup in place of veteran Josh McCown for reeling New York, which is mired in a six-game losing streak.
"He has to stay healthy, he has to get the rust off and he has to get the game plan down," Bowles said when asked what he needs to see for Darnold to return to the starting lineup.
Allen missed four games earlier this season due to an elbow injury, but has provided a spark to one of the league's worst offenses with his legs as much as his arm since his return.
Taken four slots behind Darnold at No. 7, Allen helped the Bills defeat Jacksonville on Nov. 25, and very nearly produced a last-minute come-from-behind victory at Miami, only to see tight end Charles Clay fail to catch Allen's slightly underthrown fourth-down heave to the end zone.
Allen finished with 231 yards passing and 135 yards rushing against the Dolphins, producing 85 percent of Buffalo's total offense.
"He's a competitive player," said Bills offensive coordinator Brian Daboll. "Tough, strong obviously, has made a lot of plays with his legs over the last two weeks. Can make them with his arm, too. I'm sure there's a few plays that Josh would like to have back, just like all of us when we don't come out on top.
"We're working each week to try to improve. I think he's taken steps, he's getting better."
Allen was forced into the lineup in the third quarter of the season opener due to the ineffectiveness of starter Nathan Peterman and struggled for the most part until he was injured in a loss to Houston on Oct. 14 and sidelined for more than a month.
The time off seems to have benefited Allen, who threw for 160 yards and rushed for 99 and a touchdown in the 24-21 win over the Jaguars. He made several key plays in that win and was the best player on the field in Miami, but still remains a work in progress.
"There's a lot of things, though, that we need to keep working on and harp on and improve on," said Daboll. "But each week he's been in there, there's been improvement. You'd like to hit all of those throws that we have and make all the right reads and all the decisions, but the young man is really fun to work with. Takes his craft really serious for a young player.
"There's going to be some downs. He's done OK the last couple weeks. I think that we've just got to keep grinding it out and really improving in all the stuff that we can."
Meanwhile, frustration continues to build for the Jets after they blew a 16-point lead in last week's 26-22 loss at Tennessee. It was the first time during the six-game slide that New York scored more than 16 points.
"Dumb mistakes at dumb times cost us ballgames. That's why we're in the position we're in," said Bowles. "We won't be a good football team until we're a smart football team."
Even if Darnold is able to return Sunday, there's no guarantee he will cure the team's offensive woes. Over his last three starts before he was injured, Darnold completed less than 50 percent of his passes with a pair of touchdowns and half of his 14 interceptions.
New York also could be without starting running back Isaiah Crowell, who was unable to practice Wednesday due to a toe injury.