Jared,
Doesn't having geographically located page caches reduce the doubling effect in any given location?
Squids located in the US should be caching more en-US than en-GB, and those in Europe should have more en-GB than en-US.
It doesn't happen with LRU, object accessed 100 times over the hour will be cached in same way as object accessed once. One would need ARC*-kind of thing, to handle it better, and ARC doesn't work well with COSS**, and ...
BR, Domas
* http://en.wikipedia.org/wiki/Adaptive_Replacement_Cache ** http://devel.squid-cache.org/coss/coss-notes.txt