Effect Maker: Improvement for Duplicate nodes error

When testing the new "required node" feature by adding a NoiseHelper both above and below an ElectricClouds node.

This produces the error:".... already has a body".

This is because the same code is duplicated in the shader. It's hard to think of a good reason to have duplicated nodes in the graph...

As a suggestion, perhaps this should be flagged a little more obviously by maybe highlighting one or more of the duplicate nodes in red with a tool tip - or knowing this, perhaps add "Did you mean to have multiple "NoiseHelper" nodes?" in the error output?