The bodies of two men, believed to be civilians in their 30s, were found near the town of Sheikh Zuweid.
It was not immediately clear who had killed them.
Egypt's deadliest jihadist organisation, Ansar Beit al-Maqdis, has previously claimed several beheadings of men it said were working for the Egyptian army or Israel's Mossad spy agency.
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The Sinai-based group, which last year pledged allegiance to the Islamic State group in Iraq and Syria, has regularly released video footage showing the executions of alleged informants, often by beheading.
Ansar Beit al-Maqdis (Partisans of Jerusalem) has targeted Egyptian security forces since the army ousted Islamist president Mohamed Morsi in July 2013.
Militant attacks have killed scores of security personnel, with jihadist groups claiming they are retaliating for a government crackdown on Morsi supporters.
Egypt's military has launched a widespread offensive against jihadist groups in the Sinai Peninsula.