Why does the Torah see fit to state the weight of each golden incense-bowl (10 Shekalim) and the sum total of the twelve incense-bowls 120 Shekealim)?
Rashi: To teach us that, when the Torah said above by each Nasi "Kaf Achas Asarah Zahav", it means that it was the bowl that was made of gold, but the weight was ten silver Shekalim. 1
Targum Yonasan: Each golden incense bowl corresponded to the Aseres ha'Dibros, whereas the combined incense-bowls corresponded to the hundred and twenty years that Moshe lived.
Rashi: Because otherwise we would have interpreted it to mean that the bowl, which was made of silver, weighed ten golden Shekalim.