Two Kongs enter! One Kong leaves! Two Kongs enter! One Kong leaves!
King Kong Escapes! (1967) aka Kingu Kongu No Gyakushu aka Mechanikong aka King Kong vs. Robot Kong was originally made by Toho Studios in 1967 and was recently re-released on DVD in 2009. Rankin/Bass, the animation production studio that made Mad Mad Monster Party (1968) with Boris Karloff, produced the US cut of the Ishiro Honda film.
The Japanese studio who shot the live action that makes up 90% of the movie added some interesting stop-motion shots in the traditionally convoluted script with a "Stomp Tokyo" approach to monster motivations.
Horror Hut, King Kong vs. Mechanikong
Go Go Godziller, King Kong vs. Godziller
Gargantuan Media, Kingu Kongu No Gyakushu Wallpaper
King Kong Escapes is available at: