I found out about this issue when a few users complained. It turns out google was indexing the pages, so sometimes those types of URLs would appear on a search page.
The simplest way to combat it is to have google ignore that parameter in google webmaster tools. Then it won't ever get indexed.
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I wonder how they discovered this, and whether this is truly a problem - when would someone come into a site with that hanging on their url?
I found out about this issue when a few users complained. It turns out google was indexing the pages, so sometimes those types of URLs would appear on a search page.
The simplest way to combat it is to have google ignore that parameter in google webmaster tools. Then it won't ever get indexed.