Sgt. Frog Episode 182: Keroro, Buried Treasure Special / Tamama Vs. Tamama
Episode 182 of 358 of Sgt. Frog, aired October 13, 2007, 25 minutes. Available with English subtitles and dub where released.
Episode summary
When Keroro and Fuyuki go looking for buried treasure near Grandma`s house, Keroro suffers a bump that sends him spinning back in time to the Edo period. Later, Tamama is confronted with an almost-exact duplicate of himself, but has to prove that he`s the one and only Private Tamama... if he`s not the fake. Source: crunchyroll