A similar issue occurs in SQL, where NULL != NULL. [0] In both bases, our typical "equals" abstraction has become too leaky, and we're left trying to grapple with managing different kinds of "equality" at the same time.
Consider the difference between:
1. "Box A contains a cursed object that the human mind cannot comprehend without being driven to madness. Does Box B also contain one? ... Yes."
2. "Is the cursed object in Box A the same as the one in Box B? ... It... uh..." <screaming begins>
Note that this is not the same as stuff like "1"==1.0, because we're not mixing types here. Both operands are the same type, our problem is determining their "value", and how we encode uncertainty or a lack of knowledge.
SQL more elegantly introduces ternary logic in this case, where any comparison with NULL is itself NULL. This is sadly not possible in most languages where a comparison operator must always return a (non-nullable) boolean value.
To make a deep cut: https://thedailywtf.com/articles/what_is_truth_0x3f_