Here's a new one... 
The Hardy Boys -> At The Gates 
Both feature a set of close brothers and were well liked by their respective fans. Many fans also thought that they did not have to break up as soon as they did. 
  
It then gets extended by the close friend of the band Jensen, who played with the Björler Brothers of ATG, and his two bands... 
  
Matt Hardy -> The Haunted 
Both have a small but vocal fan base who are really[/]into them. They have strong old school tendencies, and show strong comparisons with their more established contemporaries (Jericho, Slayer). They also have a really strong work ethic (constantly working/touring/releasing books/new material, etc.), as well as recently undoing switches (Matt going from Raw, to SD, and back to Raw; Haunted's vocalist changing from Peter to Marco and back to Peter). 
  
Jeff Hardy->Witchery 
Although both can be really cool when they want to, sometimes the stuff they do just doesn't work. Neither really seems like it's dedicated (Jeff always asking for time off & "retiring";Witchery's lack of new material and  touring), and sometime relies more on its image than its actual skill. Their singer had a thing for makeup for a while and we all know about Jeff's body paint fetish. When they want to, both can be really really cool. And a lot of wanna be goth fat girls seem to be into them.