output cache and webp

Hi,

I have a question around the caching version of a page, and the webp support.

I put the caching support on my website ( $this->output->cache(300) )  but i encounter some problems with the webp support.

If the first cache was from a browser who accept the webp, of course all my images will be on this format, and the people who use for exemple an iphone 6 wish safari will not see any picture during this cache time.

My question is :  is it possible to manage a double cache version of each page, and give to the visitor the good page, or any other solution for manage this kind of thing with the cache page ?

Thanks a lot by advance