Going to enter the MSX-dev'08 - Let me introduce the TEAM...

aww, i want them all!

The background scroll in Circus Charlie. Not very frequent tho.

What is not normal is the use of sprites to mask out color spill limits. Anyway i do not ever noticed that konami does this. Any example?It's normal they've done it on NES too.

Even better, look at the nemesis 2 title screen. The "2" blinks in blue and green, but the green does not seem to spill over into the "wings?". Instead you see on both sides of the top of the "2" a blue area that is almost certainly masked with sprites to hide a color spill.

in blue msx u can use LCtrl+LSft+S and hide the spries
you'll be surprised on how many times konami used the trick
see penguin adventure titles screen too

From what i can see, this trick is used in nemesis2. If it's only on the '2' having or not does not improve almost anything, as there are only a couple of pixels that can spill. Appear to be a "last minute correction" to gfx instead that a planned use of sprites.
I've not checked Penguin Adv.
The only significative use i've seen is on circus charlie- Anyway three example over a so large number of konami games is not so significative.

Simply meaningless the use of this tecnique on NES. AFAIK the NES allow for 4 colors in a 8x8 region, and if you have color clash problems with 4 colors.... you have the same graphic ability i have (that is ->0)
IMHO, If the tms had the ability to give 4 colors on 8 pixels all msx developer will be entusiast!