The fight, involving 50 or 60 people, took place in Faces and NU Bar in Bridge Street on 12 December.
The men, aged 20 and 21 and from London, were arrested on Christmas Day on suspicion of grievous bodily harm.
A 19-year-old man was arrested earlier this month on suspicion of the same offence. All three men have been released on bail.
No-one has been charged in connection with the incident which took place early in the morning of 12 December.
Police believe a sharp implement, possibly a Stanley knife, was used to stab the victims.
Eight people were taken to hospital following the fight, but have all since been released.
Northampton Borough Council's licensing sub-committee has suspended the licences of NU Bar and Faces pending a review in January.
Two men have been arrested over a mass brawl in Northampton which six people were stabbed.