If you've ever done any scripting in Maya or even tried to clean up you scene a bit I'm sure you've run into some of Maya's quirks with how it handles object names. Specifically it gets real tricky when dealing with nodes that share duplicated names and renaming whole chains of nodes.
To help demystify what's going on I thought I'd run through the development of a 'rename' tool that will cover ways I've found to resolve these issues.
Back to sunny Cali after a couple of weeks in sunny Paris ( & Normandy). 
This tutorial will outline the best way I've found to 'add' two normal maps in photoshop. This method specifically adds two normal maps it doesn't average, subtract or multiply.