I have a H.carnosa "tricolor","Krimson queen" Usually the white color is on the outside of the leaves.But i also have a H.carnosa "rubra" "krimson princess" which the white is in the middle of the leaves and not all the leaves have white on them some are all green.Since mine have been getting more sunlight i have notice some of the leaves on my "rubra" have white (freckles) for lack of a better word.
I am curious about your plant.Is that what all the leaves look like?Are the leaves thick and waxy?
the first 2 pictures are of my rubra, The last picture has my tri-color in it.
I feel really embarrassed i just realized you said H. bicolor.Just a coincidence i went to a web site and there it was. the web site i seen it on was http://apodagis.com/Hoyas/hoya_species/bicolor.html
I don't have this one and know nothing about it.But you have a nice plant.Hope some one answers your question.