I have no idea. When I open a epub, it is the only open epub. Perhaps you have started multiple instances of Sigil. How do you open the epub, via the menu or by clicking the epub? On what OS are you?
The second part is even stranger. When I open a new page in sigil, it is formated like:
Code:
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
</head>
<body style="">
<p> </p>
</body>
</html>
Nothing about painters... Is your header like the one above? What is the source of the code?