duplicate/editing textures

I encountered another problem today.  I have several colorways of a simple pattern that need to be applied.  Usually, I get one set (size, properties), then duplicate and just change the texture map.  For some reason, it will duplicate a different material than what I selected.  I have to restart rhino to get it to allow me to change it.  After the restart I can duplicate one and change the map.  It previews incorrectly though.  I went in and changed the map again, and it switched the preview of a completely different duplicate.  Please see the jpg for further explanation.  You can see the material that I chose to edit is not the same one that came up.