The Get-Content and then Select-String should help. If the string is in the file it will get returned. If not then the command will returned empty value.
Get-Content C:\listOfNames.txt | Select-String "BrazilRP"
If the "BrazilRP" occurs more than once all the occurrences will returned so you know if you got any duplicates. Same holds if the string is a part of a longer expression. For example if you search for "zil" then "BrazilRP" will be returned as well.
Also you can pipe the results out to another file:
Get-Content C:\listOfNames.txt | Select-String "BrazilRP" | Out-File C:\myResults.txt
(gc C:\listOfNames.txt) -contains 'BrazilRP'