The two men freed today were employees of Pawinder Singh and Nand Singh, who deal in natural medicines.
Police said the Sikhs continue to remain untraceable.
The four men were abducted by unidentified persons at gunpoint in Dera Ismail Khan district bordering South Waziristan tribal region yesterday.
The kidnapping occurred near Daraban area in the restive Khyber-Pakthunkhwa province.
Sardar Singh, a resident of Peshawar, registered a case against unknown terrorists in Daraban police station for the abduction of his son Pawinder Singh and nephew Nand Singh.
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Further investigation is on in the case, police officials said.
No group has claimed responsibility for the kidnappings.
Peshawar has a sizable Sikh population and there have been several instances in recent years of members of the minority community being kidnapped for ransom.