When importing, it's good to remember that the "import" really is a "merge", your scene gets some things from the pz3 but other things are not changed:
-props and figures of the new pz3 are added
-currently selected Camera CHANGED to that of the imported pz3
-document window size is NOT changed
-background color CHANGED
-document display mode NOT changed
-angles etc. of camera settings NOT changed
-render options NOT changed
-lighting angles, colors NOT changed