I would tend to think that the second 2000ml step wouldn't add much to the overall amount of yeast you have.
I think the dregs from the previous 2000ml starter, when re-pitched, would quickly go into "fermentation mode" (rather than spending time in "growth" mode). I don't have the data to back this up, but it makes intuitive sense to me.
If you want to increase the total cell count, you would have to pitch into a larger amount of wort.
Prost
-Bob