I have a project which includes a number of meshes exported from Prefab3D as actionscript. I’m wondering if I am doing things correctly placing each export’s folder each containing a copy of ASBase.as, PrefabProject.as and ASDReader, etc. in the project as is. Flash Builder 4.7 generates warnings about the duplicates saying “Overlapping source path entries…” and “ASBase is defined by multiple files: “
This doen’t seem to be fatal at the moment but I’m worried there might be some instability lurking there.

Should I worry and do things some other way?

You should set up for one export first.
lets say you give the packagename “models”
now every export can be made within this folder. with “write folder” option off. Every duplicate would be overwritted, so there would be only one class.

The second option, and is the safest (especially if you edit some classes), you export with “write folder” on, somewhere on your disk, and you move every class you need by hand into your “models” directory. (the export class+ its data classes)
You just need to make sure that you do export with “models” entered as package name.

Note that if you do not use the test AS3 Project, unselect this option as well.

if you export a series of models as class, doing one way or the other, compile after each new addition.