jemois - 4:35 pm on Jul 5, 2012 (gmt 0)
I don't understand what you mean by "verified". Are you talking about Webmaster Tools?
Yes, in WMT
This also isn't clear to me. Why would re-verifying the old site cause both sites to "vanish"?
Since the old domain was verified using the HTML file upload method and it became entirely redirected to the brand domain, the HTML file was also redirected to the brand site and the old domain became "unverified" in WMT. After verifying the old domain again (and also keeping the redirection to the brand domain) it started ranking again but only for 1 day, than it was nowhere to found in the serps.
Another strange thing is that i submitted 2 websites with BOTW, one of them being the brand site I'm talking about in this post. Both of them were approved and felt drastically in the serps from the second day they appeared in BOTW.