nnimap downloading copies

[Jay Belanger]

I've been using Gnus and nnimap to read mail from gmail for a few
months, and sometime in January it began downloading copies of the
emails in ".../agent/nnimap/gmail/FolderName".  (I don't recall it doing
that before.) I don't recall making any changes to gnus.el.  I began
dissecting gnus.el to pinpoint the problem, but quickly found that using
a partial gnus.el messed with my folder structure.  So I certainly
don't have enough information for anyone to diagnose any possible
problem, but I was wondering if anyone knew (off the top of their head): 
  * Am I misremembering and did Gnus nnimap always download the email?
  * If not, what settings could cause nnimap to download email?

Thanks,
Jay