Hey there Tammy,

there shouldn't be any problems in simply selecting the blendshapes and then the duplicate model and creating a new blendshape node.

In the attached image, I made the original (blue) then duplicated that to make the blendshape (yellow) and attached it to the blue(ball1 blendshape node). I then copied the original again (red) and attached the yellow one to it using a new blendshape node (ball2). It works fine.

Hope that helps,

Mat.