It's all original material shot by DDF, but I know what you mean. I don't know anybody else who recycles the same material to the extent they do. I think they just do it to keep their stuff on retailers "New Items" lists.
The only good thing is that they usually include caps from each scene on the back cover, so it isn't hard to figure out if you've already got a particular performance. That doesn't make it less annoying, of course.

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