Twin Eagle - Shuang Ying (Asia) (Unl) (Famicom) is an Asian release for the Famicom (the Japanese version of NES). The title "Shuang Ying" is the Chinese translation of the game's concept. The gameplay would be similar to other versions, focusing on side-scrolling action and shooting enemies.  The "Unl" likely indicates an unlicensed release, meaning it wasn't officially distributed by Nintendo or the original game developers.  This would suggest that the exact origin and development history might be difficult to definitively trace. 

Twin Eagle - Shuang Ying (Asia) (Unl) (Famicom)

Twin Cobra (USA)