csrf, ajax and form

Hi people, as I wrote in the thread subject I'm here to ask something about the csrf_regenerate.

The first question is:
is the csrf_regenerate needed? 

In my website I set csrf_regenerate = TRUE and in each view I inserted an hidden input and, when the ajax is completed, I refresh the value of this input with the php response. But there is a problem. Instead if I have two tabs of browser opened on the same page and I do an ajax request, on the page that I see all will work fine, but if I switch to the other tab I get the 403 error on each ajax request.

So I don't know how to fix that, and for that I was thinking: the csrf_regenerate is really important?