ここの夫婦ほど私たちとかけ離れた連中はまたといませんよ。
There's no one as different from us as the people here.
This is how I would translate the sentence without またと. Am I correct that this sentence works without またと?
I'm assuming that またと means "in addition/besides", but I'm struggling to understand how it fits into the sentence grammatically, and what extra nuance it adds.
The usual form is:
「[Object/Situation/Event] + は + またと + [Verb in Negative Form]」
The 「またと」 here functions to (emphatically) deny the likelihood of the [Object/Situation/Event] occurring again.
It is synonymous to 「二度{にど}と」、「ふたたび」、「めったに」, etc.
Therefore, the basic meaning of the sentence will pretty much stay the same even if you dropped the 「またと」, but it is often used to make it sound emphatic.
I'm assuming that またと means "in addition/besides"
Not quite. As I explained, it means (used in conjunction with a negative verb) something along the lines of "(basically) never again".
「ここの夫婦{ふうふ}ほど私{わたし}たちとかけ離{はな}れた連中{れんちゅう}はまたといませんよ。」
therefore means:
"You shall never see/find a couple (or "people") as completely different from us as the married couple here."