Repetition occurs for same words when case is ignored

Problem/Motivation

If I am ignoring case and I have the term "structure" defined, and the sentence "The Structure lorem ipsum structure.", I would expect only "Structure" to be targeted, rather than both "Structure" and "structure".

Steps to reproduce

Proposed resolution

If ignoring case, prune out the second instance of any term in the $needles array.

Remaining tasks

Add logic to remove repetitive terms with different casings in the $needles array.