The talented duo will remain at the County Ground until at least the end of the 2017 season.
The news is a big boost to Northants on the day Yorkshire confirmed the signing of England all-rounder David Willey.
Willey, who like Duckett and Keogh is a product of the Northants Academy, will move to Headingley on a three-year deal at the end of the current campaign.
But batsmen Duckett and Keogh will be sticking around, to the delight of head coach David Ripley.
“We are delighted that both Ben and Rob will be with us going forwards,” Ripley said.
“Both came through our Academy system and we’ve seen them grow as young players and young men during their time here.
“I’m looking forward to seeing that continue over the coming years as our Academy consistently provides home grown, first class talent.”
Azharullah also recently committed his future to Northants.
And Ripley added: “Our plans to reinforce the squad are advanced; we are looking to add depth, quality and remain competetive in all formats. We will have more to say on further signings in due course.
“We recently announced Azharullah’s extension until the end of 2017 so we’ve already got the basis of an excellent squad for next year taking shape.
“Looking a bit further ahead we are making progress in securing other key players beyond the end of next year.”