Hi Bront,

I just tested this on my local dev machine. I used Firebug to inspect the requests the browser is sending to the server.

Here's the sequence, using the single-file upload (click Browse, choose the file, click Upload):

Upload a new file to the server.
It does a POST to https://localhost/labkey/_webdav/home/%40files
Upload the same file to the server again.
Without sending any new requests, the browser pops up a dialog asking to confirm the overwrite.
It then does a POST to https://localhost/labkey/_webdav/home/%40files?overwrite=t

Thanks,
Josh