Scenario: Internal linking is pointing to two different versions of a URL, one with brackets  and the other version with the brackets encoded as %5B%5D
Version 1: site.com/test?hello=all&howdy=all&ciao=all
Version 2: site.com/test?hello%5B%5D=all&howdy%5B%5D=all&ciao%5B%5D=all
Question: Will search engines view these as duplicate content? Technically there is a difference in characters, but it's only because one version encodes the brackets, and the other does not (See: http://www.w3schools.com/tags/ref_urlencode.asp)
We are asking the developer to encode ALL URLs because this seems cleaner but they are telling us that Google will see zero difference. We aren't sure if this is true, since engines can get so hung up on even one single difference in character.
We don't want to unnecessarily fracture the internal link structure of the site, so again - any feedback is welcome, thank you. :)