Constable Chhatrapal Yadav was arrested late last night and Urvesh Yadav was detained in the early morning today, Superintendent of Police A K Saxena said.
All the five accused named in the FIR, including constables Sarvesh Yadav, Chhatrapal and three brothers Pappu Yadav, Awadhesh Yadav and Urvesh Yadav have been arrested.
The FIR was registered against seven persons including two unnamed men after outrage over the incident.
Taking note of the incident, Katra Sadatganj police outpost in-charge Ram Vilas Yadav was been suspended and two constables -- Sarvesh and Chhatrapal -- were terminated from services yesterday, Saxena said.
While the two constables have been booked under Section 120B (criminal conspiracy) of IPC, the three brothers have been booked under Section 302 (murder) and 376 (rape).
The two girls, who were cousins and aged 14 and 15, went missing from their house on the night of May 27 and their bodies were found hanging from a mango tree in the village in Ushait area on May 28.
The postmortem report of the two girls confirmed that they were raped before murder.
A lot of hue and cry has been created by the opposition, with BSP supremo demanding a CBI probe into the matter.
The family of the two victims had also demanded a CBI probe, saying they had no faith in local police which was "hand in gloves" with the accused.
The father of one of the girls had yesterday called for transferring the case to the agency alleging that the role of police was "suspicious".
"The role of police in the entire incident is suspicious. Had the cops acted timely and did not showed laxity, lives of the girls would have been saved. They were hand in gloves with the accused," father of one of the victim had said here.
The Uttar Pradesh government has also sanctioned financial assistance of Rs 5 lakh each to the family members of the victims while directing officials to provide security to them.