70%cocoa :
Hi DG!
No, white is totally different to splash. Splash can look white, but genetically it is totally different.
Splash is caused by Black + Two doses of Blue.
White is caused by two doses of White (which is recessive).
White also masks all other colour genes. The word for this type of masking colour is Epistatic.
With the Black and White Runner combo, your friend will most likely get black ducklings. But if the Black one only has one dose of the black gene then some offspring will probably not be black. Also, it depends on what the White bird has along with the white. White masks any other colour. White birds are meant to be mallard pattern/colour under the white but in reality they could be anything.
So, your friend could get an interesting mix
Hey 70%
She got 5 black runners from holderreads, and 5 whites, and sold them all but a black drake and a white hen, so I think they are pure....