What's the plural form of nonuniqueness? Here's the word you're looking for.
Answer
The noun nonuniqueness can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be nonuniqueness.
However, in more specific contexts, the plural form can also be nonuniquenesses e.g. in reference to various types of nonuniquenesses
or a collection of nonuniquenesses.