Maybe I am thinking too much but I could't pretend I am totally comfortable with the sentence.

This is from a book (He was a lisp issue):

Plurals presented a considerable problem, but I worked around them as best I could; "rivers," for example, became either "a river or two" or "many a river."

"many a river" is acceptable, but I don't think "a river or two" can be the equivalent phrase to "rivers" because, I believe, plurals mean "more than one" and so can't include "a river."

Grammatically, I think I am correct, but don't know in terms of the practical meaning. "a river or two" can be used for "rivers"?

Thank you,

Part of his problem (and some of the humour of the book) is that he is trying to find impossible equivalents just to avoid lisping his /s/. As he said, he worked around them 'as best he could', i.e. not always perfectly. 'A river or two' suggests more than a single river, that is all.
I see.

I seeeee.

Thank you, humorous lines are hard to understand, thouth that's why I'm working on this book.