Both of these terms have to do with the concept of justifying moral judgments or principles.

Both ideas connect with the idea of a method that can justify judgments and principles. If we have no method, then we may say that all judgments or principles are on the same level. They are all equally justified or unjustified. That one possible meaning for the phrase 'equally valid.'

Another possibility is that we have a method for justifying judgments and principles but it cannot provide more of a justification for judgment A than it can provide for judgment B. Or, it cannot provide more a justification for principle A than it can provide for principle B. In cases like this, we might say that A and B are equally justified or equally valid.