Ailion, the Rogue developer, has confirmed there is an upcoming fix to the Ranger Pets Rend attack since it does not stack with other Ranger pets. This causes probably around a 200-300 DPS loss. I would assume this means it will get a fix for sometimes not being used as well? Time will only tell. Too bad this hotfix has yet to be released.
Thanks for the heads up. This will be hot fixed soon.