Copying a layer to a new layer on the same page

[epioletti]

I am using Visio 2003. 
I have many layers on one page called Phase1, Phase2 and Phase3
Each layer may have:
      Shapes unique to that layer
      Shapes common to some layers
      Shapes common to all layers
I want to copy layer Phase2 (This layer has shapes unique to Phase2 but also in Phase1 and and Phase3) to a new layer (Phase1.5)
Thee way I do it is
      Select Type -> Layer->Phase2       
      Format -> Layer 
          *This is where I have a concern.  The layers that are automatically checked in the "Layers On" dialogue box are Phase1 and Phase2.
                 If I also check Phase1.5,   then Phase2 is copied to Phase1.5 but it's also copied to Phase1
                 If I uncheck Phase2 and check Phase1.5, then Phase2 is copied to Phase1.5 but the shapes in Phase2 disappear.
I'm not sure what to do at this point.   Any help would be appreciated because I've spent alot of time creating these layers and I want to
extend these layers to new layers.
Thanks,
Betsy