%252F vs. %2F

I built a module several months ago and released it to a client who has had it working up until a few days ago on their site. The basic premise of the module is to track and record forwarding redirects. (i.e. A customer comes to http://www.example.com/redirect/http://www.example2.com and Drupal makes a database entry before forwarding the user on to http://www.example2.com.) Originally, I was URL encoding the URL that the customer would be forwarded to as: http%3A%2F%2Fwww.example2.com. However, a couple days ago, this stopped working and now whenever I try go to the redirect page, I got a 404 page not found error. Instead, I have found that double-encoding the URL makes the redirect work just like before, such as: http%253A%252F%252Fwww.example2.com. Unfortunately, I'm not in charge of generating these URLs (it is an app that someone else built) and would like very much to not have to change the standard from %2F to %252F. I'm not sure what changed in the last couple days to cause this, but neither Drupal nor the app have been updated in the last few days such that it would coincide with this error. Does anyone have any suggestions on how to not have to do double-encoding and keep the original URLs as they are? Thanks!