Great question — answering as the UphillTech team:
Just changing every occurrence of a single word won't help you. Google won't penalise you for duplicate content, providing that content was first spidered on your website. But Google will merely consider it canonically identical to another page if it's insufficiently different, regardless of whether you use rel="canonical" tags. That means your "new" pages won't be indexed and won't provide you with any benefit.
Full answer by GeoffAtkins: https://webmasters.stackexchange.com/a/134385 (CC BY-SA 4.0).
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