1、 They look at an organic being as a savage looks at a ship, as at something wholly beyond his comprehension. 有两个并列的as引导的比较状语从句对吗?

回答：这里不是比较状语，as在这里相当于as if、 just like，是个连词（意思是”就像，就好像是“），完整的句子是they look at an organic being as a savage looks at a ship,as  a savage looks  at something wholly beyond his comprehension. 比较状语从句应该是 as .... as ... 的结构，A 和B 一样+adj. 的结构。

2、 But however amazed （our descendants may be)  at how far from Utopia (we were), they will look just like us.

这个句子前半句由at分开成两部分，前半部分恢复到陈述句语气应该是： our descendants may be amazed  at ...; 后半部分是at的介宾结构，正常语序是 we were far from Utopia，句子中用however +adj. 不论多么... 的结构来分别强调形容词amazed和far。这半句的意思是：不论我们的后代有多么吃惊对于我们离乌托邦有多远。

那第一句可以理解为两个并列的as引导的方式状语从句吗？

这里是一个方式状语，非常棒