DWF6 does not output the Layer names from the second layout onwards while
plotting 'All layout tabs'.
The second layout depends on the sequence, the layouts are sent for
1. Create a drawing with multiple layers and layouts.
2. Plot the drawing to DWF6.pc3 by choosing 'All Layout tabs'.
Open the resulting DWF's and notice that only one DWF will have all the
layer names where as the
rest of the DWF's doesn't.