Bifocal Depth of Field

Hi all,

I'm doing an app that simulates some types of vision problems. One of them deals with the ability to see well in both near and far distance but not in mid distance.

Something like this:

Depth of field works fine if I want to focus at one point, like this example, but I found nothing about to do it with two focus (close and far distance in this case). I tried anyway to duplicate Depth of Field in the same camera and put another focus point, but it doesn't work.

Here's more examples (1 & 2) of what I'm looking for.

If anybody knows anything that can help me I would appreciate it very much.

Thank you in advance!

UPDATE

I tried to duplicate cameras and set diferent clipping planes. I put in each camera its depth of field but it still doesn't work. The near camera blurs all the screen render and it clipping mask has no effect at all.