Middle-Clicking Bookmark in Start Page Opens 2 Equal Tabs
BOOKMARKS Open Bookmarks in New Tab (must be checked for bug to happen) Latest 32-bit snapshot.
I enabled "Open bookmarks in new tab" but was unable to reproduce this. I tried both middle-click on a Speed Dial, and middle-click on a Bookmarks Bar bookmark. Both opened the bookmark in a background tab as expected.
1.3.501.6 (Developer Build) (32-bit) on Windows 64-bit