OOOPS,
I have been working for quite some time with the new interface now and I never experienced the diplicate note issue except when I used multiple tabs. Today all of a sudden I have > 30 duplicate notes containing different states of my note I am currently working on. Luckily, the one last modified was the complete one.
I immediately moved away to the old version because it allows me to delete multiple notes. I will stay with the old and still much better version until something happens with the new interface.
And looking to the update schedule I am not very optimistic that this will be any time soon. Considering the recent development with Evernote I think I need to switch to another solution soon. I have a very bad feeling because at the moment nothing much is happening and not just with the Web version. What are they doing?