It might be original. Atari used a version of the Sanyo in some of their machines. Should be very similar to the Nintendo Sanyo, only it runs on 120v and takes standard non-inverted video.
But, debating which monitor is "original" is moot - Atari (and most manufacturers) frequently used different monitors throughout the production run of particular games.
Atari did use some really crummy monitors in some games though - the infamous Disco monitor, and the Matsushita.
-Ian