The men, aged 58 and 38, were arrested on suspicion of possession of articles for use in terrorism and other related offences.
Speaking on Sunday, Detective Chief Inspector Hamilton said: “Our investigation into this matter continues and we would appeal to anyone with any information relating to this incident to contact police on 101.
"We are particularly keen to hear from anyone who was travelling through Dungiven on Thursday night, 31st August and who has any dash cam footage.”
Initially police stated the poster carried details of three serving officers but in an update they said the information was incorrect.
They also issued a further statement emphasising that a woman wrongly linked to the PSNI on the poster has “no current or historic links to the Police Service”.