This is a common problem, not that it makes you feel any better.
If you can,
Sand the contrasting woods separately
Use a sanding sealer
Clean the sanded area thoroughly with acetone or mineral spirits and compressed air.

You may also encounter bleeding when applying finish,
Wipe with solvent before applying finish
Apply light coats in a single pass
Move from light to dark
Spray if necessary

Experiment on a practice piece

What you are tying to do is "seal" or fill up the pores of the wood, especially the lighter wood. This way the padauk sanding debris has a much more difficult time contaminating the lighter wood, no pores to get into since you sealed them.
Sealer can be brushed wiped on with a rag or sprayed. Will spraying is best with pesky woods like padauk, you can usually just wipe it on, you will be sanding after all. The padauk shouldn't need that many goats  of sealer. If it starts to build, you have enough.

An easier method is use a air gun to immediately after the sander.  It takes a little coordination but it works.  the disadvantage is that you are blowing dust everywhere!