Powershell: Using .Split on Filename functioning differently based on filename capitalization

Thanks to @Lee_Daily

$FileA.BaseName -replace $FileA.Extension, '' will convert this >>> 'IMG_1468.JPG.JPG'<<< to this >>> 'IMG_1468' <<< after that, you can simply add the .Extension back onto the remaining

I still have no idea why .Split was acting the way it was, but rewriting the $newName definition as advised by @Lee_Daily seems to be agnostic to capitalization (thus solving my root problem):

        $newBaseName = $file.BaseName -replace $file.Extension
        $newName = $newBaseName+$file.Extension
        Write-Host "newName =" $newName
        $file | Rename-Item -NewName { $newName } -WhatIf        

This now gives me the output I was looking for even when the input is the capitalized value of $FileA:

extCheck = .JPG
oldName = IMG_1468.JPG.JPG
File.Extension = .JPG
newName = IMG_1468.JPG

What if: Performing the operation "Rename File" on target 
"Item: \UNC\Path\To\File\IMG_1468.JPG.JPG 
Destination: \\UNC\Path\To\File\IMG_1468.JPG".