不多余,这是传统英语中最正规的说法.
其实than是个连词,后面接的是比较状语从句,这个从句往往以省略句的形式出现,如果把它补充完整,就是：
My home is farther from the school than yours is far.
He is older than I am old.
但实际上没有人这样说.人们都会省略与主句相似的成分,有的人觉得省略得太厉害了就不正规了,就保留系动词be；但口语中大多数人连 be动词都省略的；更有甚者,有的人把than后面的从句的主语都改成宾格了.如：
Bill is shorter than I （am). = Bill is shorter than me.
She is as slim as I (am). = She is as slim as me.