One and the same

A and B are one does not mean they are identical in modern English; it means they are a single unit. 'One and the same' is a fixed phrase.

Thanks, Mister Micawber. Can you explain what you mean by single unit? Does it mean they're the same entity? If so, how is it different from 'one and the same'?

"A and B are as one" sometimes means you can't tell them apart, and sometimes it means they function as a unit, as MrM offered for "A and B are one."
Two peas in a pod
Tweedle Dee and Tweedle Dum

I'm not sure "identical" doesn't have two meanings. "Identical twins" are two separate people.
Samuel Clemens and Mark Twain are one and the same. Would

Can you explain what you mean by single unit? Does it mean they're the same entity?-- Yes, that is what I meant.

If so, how is it different from 'one and the same'?-- To me, 'one and the same' means they are identical concepts, like Avangi's 'as one'.

And then there are some marriages. The minister says, "You are now one."

I'll try this with an example. Suppose we say: loving and sharing are the same. Wouldn't every other option be correct here? Loving and sharing are one (as well as) loving and sharing are one and the same.

AnonymousI'll try this with an example. Suppose we say: loving and sharing are the same. Wouldn't every other option be correct here? Loving and sharing are one (as well as) loving and sharing are one and the same.

No. "One and the same" is a fixed expression meaning that one thing has two names.

Elizabeth Peters and Barbara Michaels are one and the

Hi, GG.
Is "No" your reply to the OP's first post?

Which question?

Thanks, -- A. (sorry, can't edit)