Ok here it is.
basically everything works well. it's just when i select another address (than the default selected) in address view, starts this issue (2x click on Next for address and payment views)
i also discovered another problem (maybe it's only my problem).
When my workflow is the one describe before, i had to add a second time the cart view after address view, in order to allow customers to view that Taxes are changed according to their address.
If we could have an "Review" view to let customer review everything before payment it would be great. However then only thing we can do it's to create another step in the process and to place again the previous views... but it doesn't allow some layout changes without modifying the previous views.
i mean if i have 3 steps in the checkout workflow: cart, address and payment.
if i create a 4th steps in which i replace cart, address and payment (like a review view as confirmation view before payment)
in this 4th step each change on 1 of the view (payment, cart, address) will change also the steps 1,2 or 3 of the workflow layout
thx