I was running into a similar problem. None of the Delicious.com plugins for Chrome will both save the bookmark to Chrome's bookmarks and to Delicious. The ones that say they sync are syncing the bookmarks you set with them, which do not appear in with the regular Chrome bookmarks.
I want to just press the star and have it saved to Delicious. I did find one that did this, though it's a bit rough. Chromium Delicious plugin by oleg.atamanenko, intercepts the regular Chrome "star" for bookmarking by bringing up the regular Chrome bookmark dialog box briefly, saving it, then brings up a dialog to save to Delicious with suggested tags and the like.
This fits my needs, as I plan to sync my bookmarks directly/manually with Delicious every few weeks so I can get anything I neglect to tag tagged. And I don't use folders for my bookmarks. (And I'm importing my bookmarks into a wordpress install and sorting them by tags...)
I've tried about 6 plugins and this is the only one I found that saved to both delicious and to chrome's bookmarks. I may be incorrect in this conclusion, but that's what I was seeing and what meets my needs best.