Many websites today publish the similar content to explain same concept in different words just to avoid copyright issues. It's good with respect to the end user since all of us cannot understand things explained in some way. Some of us understand things when explained differently. The problem starts when those different ways are copied and pasted. As far as we are adding value by explaining same thing differently its good but not simply copying things.
Is content duplication causing depletion of natural resources ? Be it resources required for manufacturing the storage devices or computing devices.
On the contrary we could be more creative and innovative in publishing the content. Creativity should be used in publishing the content which is not available on the internet or the content which adds value. Internet should be treated as the source for sharing the content which is not known to others, instead of duplicating the content.