.htaccess adds new characters

I’m using a .htaccess file on my site to redirect to different categories on my blog. The only problem is that when you use the .htaccess address, the blog entries now have the character ? in place of the first space wherever I use double spaces. If you use the normal address to view the category it appears normally. If you edit the post again in WordPress, all the double spaces are converted to single spaces and the character disappears. Does anyone know what’s going on?