See this gif for more info:
It looks like I can reproduce it only once for every page refresh. Meaning, if I try to copy-paste again without refreshing the page, it would work fine. If I refresh the page and do the above, it would happen again.
It was tested with Chrome 33, OS X 10.9.2
I've tried to test with FireFox, but couldn't reproduce it, so looks like Chrome specific.