Why the Pareto front from paretosearch becomes coarser when I define the starting points?

Recently I am using paretosearch() to compute the Pareto front for a multiobjective function and I noticed an odd behavior: the number of points in the pareto front decrease when I pass a matrix of initial points via the option 'InitialPoints' option. For example, 10 starting points produce a Pareto front with ~400 points, whereas 1E4 starting points give a Pareto front with only 12 points. Why does this happen? Is there a way to overcome this behavior and fix the number of output points from paretosearch()?

Thanks

Davide