Not sure how to get two tone in a mold... They look individually placed or like buttercream to me. Maybe you could go back over every other one with petal dust?
AI've done this...just a different colour in each mould hole....tedious, but doable. It would be easier to use one of your small nozzle piping tips to punch out the colours and roll out the balls yourself.....faster.....
ARoll balls - tedious and tlme-consuming.
Maybe give the client two quotes - one for s two-color bead border and one for a single color.
Like Melmar said I would just dust with petal dust. You could use a very small brush and be really careful. Looks like any way you do it, it will be time consuming, but I think this is the easiest option.
Based on the size of them they look like the Wilton sugar pearls in green and white. They also have pink, yellow and blue. Still would be tedious to place them all on the border individually.