Metal Slug 1 beta background graphics?

[Dampfwalze]

I stumbled across this video on YouTube:

After minute 14:25 the guy presents background graphics that seem to be slightly different to the actual Metal Slug 1 backgrounds.

Does somebody know where to find these? Couldn't find them with Google.

 

[Yagyu Jubei]

I wonder if those graphics were from a dev unit or generated by some type of debug menu. I'm curious as well...

 

[Xian Xi]

From what I remember they are already in the carts C roms.

 

[Dampfwalze]

From what I remember they are already in the carts C roms.

Thanx xian xi! it's incredible how much they squeezed into this cartridge.