Could you explain what you are trying to do?
We did solve the double error message in
#2593

Provide a solution to a tracker that had none! Didn't know the quality of the trackers were that bad! Think my solution is better. Maybe it will be reconsidered when error handling is properly refactored.
Closed for now!

Your solution consisted in changing a string. Did not make sense to me. :)
from: $this->setMessage(JText::sprintf('COM_USERS_REGISTRATION_SAVE_FAILED', $model->getError()), 'warning');
to: $this->setMessage(JText::sprintf('COM_USERS_FAILED', $model->getError()), 'warning');

It looks like com_user is the only component implementing a dubble layer in the message. Because someone felt the need to express that, I maintained that in my solution. Because the message already contains the activity and the actual message for the action that went wrong, I changed the controller message stating the component. So in my solution it would say Useradministration failure: registration failed: error saving .....

For components with more than one activity and more than one action that could go wrong that would put things in perspective. So, when something goes wrong with a tag it would provide the right context.

This would require a consistent implementation, hence I referred to refactoring. Maybe they even find this not needed. But this is how it is implemented in com_users. Would require another pr for the other controllers and maybe more for other components.

Had not seen the other tracker/pr. Checked in 321 and the message was still used. Just wanted a solution, so the tracker could be closed.