Some strains of blue pearls throw amber shrimp and snowball shrimp along with the blue ones.
I bought my blue pearls on AquaBid from 3 different sellers and I too have quite a few ambers. I cull them though and the blues are finally starting to win. There are more blues than ambers now.
ambers
blue pearls
While the ambers are pretty, they are not what I thought I was buying and I was a bit miffed that none of the sellers mentioned that they would produce ambers and snowballs along with the blues.
They are all in the same tank on white substrate. I moved some to dark substrate and it made no difference with mine.