Wouldn't 同じぐらい be used for quantitative comparison rather than qualitative? I don't think you can use it to say humans and puppets are about the same.
Check the WWWJDIC examples below to see what I mean.
この辞書は君のと同じぐらい役に立つ。
This dictionary is as useful as yours.
その木は屋根と同じぐらいの高さだ。
The tree is about as high as the roof.
ぼくは君と同じぐらい上手に泳げる。
I can swim as well as you. [M]
めぐは、けんと同じぐらい背が高い。
Meg is as tall as Ken.
トムはお父さんと同じぐらいの背の高さだ。
Tom is as tall as his father.
リンダはメグと同じぐらい上手に踊れる。
Linda can dance as well as Meg.
ルーシーには私と同じぐらい友達がいます。
Lucy has as many friends as I do.
私の弟は私と同じぐらいよく勉強する。
My brother studies as hard as I do.
私は父と同じぐらい背が高い。
I am as tall as my father.
小説はおとぎ話や神話と同じぐらい古い。
Fiction is as old as fairy tale and myth.
彼はお父さんと同じぐらいの背丈だ。
He is as tall as his father.
彼は私の父と同じぐらい背が高い。
He is as tall as my father.
彼は彼のお父さんと同じぐらいの背の高さである。
He is as tall as his father.
彼は父親と同じぐらいたくさんの本を持っている。
He has as many as his father does
彼女には私とほとんど同じぐらいチャンスがある。
She has no less chance than I do.
彼女は君とほとんど同じぐらいの背の高さだ。
She is almost as tall as you.
彼女は母親と同じぐらい美人だ。
She is as beautiful as her mother.
What you might be able to say with 同じぐらい could be ...
人間は人形と同じぐらい自由です。違いは誰が誰に扱われているだけです。
Humans are as free as puppets. The difference is who is manipulating who.
(lack of mistakes not a given