Those people should ideally have different titles as a way of "checking your work" as a manager. It's easy to let personal bias slip into who you judge to be a $50,000/yr X and who's a $200,000/yr X. But if you call one of those people Junior and one of those people Senior, you at least have to justify it under consistent criteria, and your team can call you out on it if it's clearly unjustified.
Only if your categories don't have clear criteria for who falls into which one. Which shouldn't be surprising: For all the hand wringing about how some people are far more productive no one in software business has yet found a way to measure software developers work performance. It's always just "I think that ...".
