Don't allow duplicate "tags" with grammatical differences, caps/no caps, etc.

Tags – the Aha! system allows you to create the same tag multiple times with “caps” & no caps. Example: “National” and “national” – they are created as separate tags, even though it's the same thing, just grammatically different. The tag list ends up being really long when this is allowed and it's difficult to manage and affects filters when searching or tallying data for reports if the user is unaware of the duplication of tags.