Its not quite as simple as that.
In order to clone a ship to a new slot additional class files are required.
However the Yorktown installation did include a spare ship class which you can use.
ShipAsheUSS$USSHornetCV8_42
USSHornetCV8_42
You can duplicate the Yorktown entries in chief.ini and ships.ini and replace the Yorktown name with those.
That will make USSHornetCV8_42 appear in the menu
Finally - in technics_ru.properties add
USSHornetCV8_42 USS Enterprise CV6 - 1942
That will swap the Enterprise name for Hornet in the drop down menus.
If you are working on the skin obviously the name on the stern must be replaced.
Check the position of the "text box" on the alpha channel when you do this. Keep within the alpha cut area.
Try modifying the weathering and the paintwork on the hull so that it looks a little different.
For a major visual change try changing the flight deck to give it a blue camo wash and maybe change the white lines a little. Look at original photos for inspiration, though good photos of Enterprise in the early 42 period seem to be rare.
You might inspire me to do the full model
The info I have on armament for Enterprise at Midway is:
8x5in; 4x4x1.1in; 34x20mm; 6x0.50cal --- so Enterprise has a greater number of 20mm Oerlikons compared with Yorktown but loses most of the 0.50cal Machine Guns. Locating the new guns will require some re-modelling of the gallery walkways. The re-modelling of the bridge structure required is pretty easy stuff.
On the subject of spare ship slots. HSFX6 still has spares I think, named Ship0, Ship1, Ship2, Ship3, Ship4.
At least they were retained in HSFX5. These can be used to clone ships as I've described above.
Except use --- Ship$Ship0 etc
Ashe