When I developed a bilingual site, I simply added an "_x" with x being either "e" or "f" to denote english or french... so for example... I'd have contact_e.html and contact_f.html
As long as you follow a naming standard like this, you shouldn't find any problems... and this could also go for the naming of your gifs. Then you wouldn't need 2 folders... you could have all your files in one folder that accessed just one image folder, therefore eliminating the need to copy your gifs. If your gifs contain text, label them as such... clickme_e.gif and clickme_f.gif
Just a little thing I used and it worked out well... Hope this helps!!