I am lacking time for posting messages in this board at the moment, but since this topic seems to arise so much debate, I will do it anyway.
The Totti/Del Piero dualism is just the unmpteenth remake of previous dualims that have opposed so many players and fans in Italy in the past.
Whenever they are lucky enough to have two world class players in the team at the same time, italians will always try to antagonize them with each other instead of rejoicing for the fact that this is added value for everybody.
The most striking example of this tendency was the rivalry between Bartali and Coppi, the two legendary italian cyclists who won nearly everything on the international scene in the post WW 2 period. It's as if Italy had produced both Eddy Merckx and Lance Armstrong at the same time, and yet the country was bitterly divided between the pro-Bartali and the pro-Coppi camps.
This rule has been repeatedly acknowledged in football as well. Today it is Totti vs Del Piero, but yesterday it was Del Piero vs Baggio, and the day before that Baggio vs Mancini, all the way back to the Mother Of All Duels : Rivera vs Mazzola.
Of course the fact that one played for Inter and the other for Milan may have helped, but it's quite ironic that while brazilian fans didn't bicker much about the pertinence of aligning Gerson, Tostao, Pélé, Rivelino and Jairzinho simultaneously in WC '70, the then italian coach Valcareggi would have been crucified for letting Mazzola and Rivera play together. But then again, he was still crucified by the Rivera supporters for letting the latter enter only 6 minutes from time as a sub for Mazzola in a final that would have seen us demolished by Pélé's Brazil anyway, Rivera or no Rivera.
The Del Piero/Totti controversy bears one big resemblance with the MOAD (Mother Of All Duels) : a lot like Rivera seemed to be under the influence of Mazzola with the NT (except for the 1970 semi where he scored the decisive goal in the legendary 4-3 win over Germany), Del Piero clearly suffers from Totti's leadership in the squadra. However, Mazzola and Rivera were much more similar players than Totti and Del Piero are today, and their coexistence on the pitch would have called for a massive revolution of Valcareggi's catenaccio. This isn't true in the present case : Godot and the Pupone can do well together without stepping over each other's feet, and they could indeed form an impressive attacking trio with Vieri.
As I said however, whereas an in-form Del Piero certainly is an asset for any team, the abundance of strikers that Italy whitnesses at the moment does not make him indispensable. This isn't true for Totti, unless we manage to naturalize Zidane..