That would be 4.2.9.3 in the current version. It requires the same material "or shall be of any appropriate material listed in Table 4-3 and Figure 4-1. Except for nozzle and manway necks, the material shall be of equal or greater yeild and tensile strength and shall be compatible with the adjacent shell material...".
So no, it does not need to be the same material, but there are restrictions on what it can be.