Affirmative. Browsing through the [opscode-cookbooks/dmg](https://github.com/opscode-cookbooks/dmg) codebase, they use the checksum provided in [remote_file command](https://github.com/opscode-cookbooks/dmg/blob/master/providers/package.rb#L37) which ensures that the file is not downloaded again if available in [cache](http://docs.opscode.com/resource_remote_file.html#attributes).

So when there is a checksum mismatch(with the file in cache) file is re-downloaded from the server. I couldn't find an option to do remote file checksum check for the downloaded file.

I dug around their issue tracker and closest issue i found is [CHEF-712](http://tickets.opscode.com/browse/CHEF-712?focusedCommentId=13404&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13404) which is still unresolved.