The 17-year- old wingers featured together for the first-team against Castleford Tigers in April and have impressed in their senior appearances this term.
Innes, in particular, has scored three tries in four games, earning man-of-the-match in that Tigers contest.
Huddersfield head of youth Andy Kelly admitted: “It’s brilliant to see them sign. I think for me as head of youth, but also for the coaching staff and talent ID, the aspiration is to see these players play at the highest level.
“It is justification for all the hard-work, and whilst I can’t name every name, Sean Folan heads the Talent ID team.
“They’re out every weekend scouting and when they bring a young player to the club, the justification of all that work is to see them go on and become Super League players at the highest level.
“Everyone is really pleased to see the Senior twins sign contracts.”
Kelly added: “We’ve had five debutants this season with Oliver Russell, Jake Wardle and Sam Hewitt plus the Seniors, who have all fronted up really well.
“It bodes really well for everyone else. The pathway has been opened up and you can see how everything works from Scholarship to Academy to first-team, the pathway is clear and it works.”