Help me with with this sentence
Given equal opportunities, the twins having identical brains would have tested at roughly the same level.

如果具有相同的机会, 大脑相同的这两位孪生兄弟本当测出大致相同的水平.

Why do you say "这两位?" Omitting it is also correct.

What is 本当？

Question

Help me with with this sentence
Given equal opportunities, the twins having identical brains would have tested at roughly the same level.

如果具有相同的机会, 大脑相同的这两位孪生兄弟本当测出大致相同的水平.

Why do you say "这两位?"  Omitting it is also correct.

What is 本当？

Answer

It means "should".

Answer

“这两位” equals "these two (persons)",so "这两位孪生兄弟" literally means "these two twins".Chinese idiomatic expression is different from English here.It stresses measure words.Usually in formal expression these measure words cannot be omitted.If you omit "这两位" here,then the sentence would sound weird.You can substitute "对" for "两位"(a pair of),which is also a measure word.
“本当” is the abbreviation of “本来应当”,it can be simply translated as "should have","would have".

Answer

得到相同的机会,这对有着相同大脑的双胞胎会在大致相同的测试水平。 
这两位 refer to the twins
would have translated into  本当