Cache not expired, but files will still download and overwrite

The cache expiry date is one month. It is sent with the headers, but the files are still downloaded and overwrited every time I reload the page.

I am using Mozilla Firefox CacheViewer to view the cache.

How开发者_C百科ever, in Google Chrome they are not overwrited. Only the Last Accessed time is updated. I am using ChromeCacheView to view the files.

Could anyone help me a little bit?

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When I click on the address bar and type in my website address in firefox, then Firebug displays 38.3 KB (36.4 KB from cache).

When I press F5 in firefox, then Firebug displays 241.1 KB (10.9 KB from cache)

This means that Firefox controls the way the cache is being used by the browser.