Is an absolute absolute?

Apparently Italian couples wishing to divorce and unwilling to go through the lengthy procedure required by Italian law are setting up false addresses in this country and filing for divorce here.  The High Court is being asked to annul nearly 200 divorces which have been obtained in this way.  My understanding always was that a decree absolute was inviolable - the problem of course is that the parties to such a decree may have gone on to remarry on the strength of that decree, and where does that leave such a second marriage, and any children which may have ensued?  I was also fascinated to learn that the office of The Queen's Proctor still exists!