In Windows I use, beside the main Firefox installation, one or even two "Firefox clones" for different purposes (specifically oriented addons and configurations, light configuration without addons, configuration for a different user, etc).

A clone of Firefox is a browser that is identical to Firefox except the name.

(It may have more - but not less - features than FF and it must be installable beside Firefox, not on top/instead of it. So, a clone is not a replacement/exclusive alternative of FF: in the way Swiftfox is, taking all previous Firefox extensions and configuration.)

For example, in Windows, Pale Moon, Cometbird and Wyzo are FF clones (but they do not have Linux support). Basically, Flock browser would also qualify, and it had support for Linux: but it was discontinued.

What remains as closest to being a full clone is Seamonkey, has support for Linux, but it is not a complete clone (although it can use a lot of FF extensions): themes are not working, the interface is in general different and rather primitive. It has the merit of keeping the pace with FF 4+ (in contrast with Swiftweasel, for example.)

Are such more browsers available in Ubuntu?

(As for comments asking why I "really" need these clones, I am just used to doing that, I like two separate Firefox-like browsers: why pleasure, just like curiosity, would not be enough??)