excelStyleFiltering search duplicates records when filteringIgnoreCase is set to true

[mmart1n]

Description

If we have the following data:
[{ProductID: 0, ProductName: "Coffee", ...}, {ProductID:1, ProductName: "CoffeE", ...}, ...]
and we have set filteringIgnoreCase to true for the igxColumn with field: ProductName,
within the excelStyleFiltering search list we observe both values: Coffee and CoffeE

• igniteui-angular version: 10.1.x, 9.1.x
• browser: any

Steps to reproduce

1. Open the following sample: https://stackblitz.com/edit/excel-style-filtering-ignore-case
2. Open the excelStyleFiltering for the ProductName column

Result

Both records exist: Coffee and CoffeE

Expected result

To have a single entry for Coffee and CoffeE