Hey Jom
Problem is, from a search engine perspective, those are four duplicate pages & from a linking perspective, they are four different pages that you could see your link popularity shared between. Neither of which is ideal.
I would certainly deal with this but it needn't be an arduous task.
1. Set up a rewrite rule to change all URLs to lowercase and 301 any non lowercase ones, something like this in your htaccess should do the job assuming you are using a LAMP environment.
RewriteEngine On RewriteMap lc int:tolower RewriteCond %{REQUEST_URI} [A-Z] RewriteRule (.*) ${lc:$1} [R=301,L]
2. Add an automated lowercase canonical to all of these pages so they canonicalise to the lowercase version.
3. Try to replace the links so they all use lowercase. If this is a dynamic site it should be easy but if not, you could still do a string replacement across multiple files. You could write a little script to automate this if it is a huge job from the sitemap (of lowercase URLs of course.
Certainly worth doing and should not be too difficult with a bit of smarts applied.
Hope this helps!
Marcus