Let me offer a real-world example. the missions of Judicial Watch vs. the ACLU.
Judicial Watch, Inc. is a conservative, non-partisan educational foundation, which promotes transparency, accountability and integrity in government, politics and the law. Through its educational endeavors, Judicial Watch advocates high standards of ethics and morality in our nation’s public life and seeks to ensure that political and judicial officials do not abuse the powers entrusted to them by the American people. Judicial Watch fulfills its educational mission through litigation, investigations, and public outreach.
The ACLU dares to create a more perfect union — beyond one person, party, or side. Our mission is to realize this promise of the United States Constitution for all and expand the reach of its guarantees.
Not the same but one would think they both are out there to protect citizens against government abuse. I think they would both agree with that goal. But, their biggest bias is who they choose to protect against what government action.
Personally, I see the work of both as useful. I don't agree with either organization on all the issues they take on. But, I think they both should exist.