Enough of that diversion for the time being. I'll return to that later (i.e. the PP2 'prop' field having an '_1'-type suffix, causing the incremental count on the internal name to start from a different number)

Back to my initial three test props (SlicerSword, IcyingLight, and Persian_Sword) to try and work out why the suffix on internal names of the first two follows the 'no suffix', ' 1', ' 2' sequence, while the Persian_Sword uses an underscore instead of a space.

What's different?

a) The Persian_Sword uses internal geometry,the other two use external. b) The 'prop' field of the Persian_Sword PP2 doesn't have a ':1'-type suffix, the other two have one. c) The 'prop' field of the Persian_Sword PP2 has an underscore in it,the other two don't. d) The 'prop' and 'name' fields of the Persian_Sword PP2 are identical, for the other two they aren't.

But also consider the tests with 'TheCube.obj'and 'TheCube.pp2'. It's internal name follows the pattern of the SlicerSword and IcyingLight. But in cases (a), (b) and (d) it matches the Persian_Sword...

So what happens if we add an underscore into the 'prop' and 'name' fields of our cube PP2 ?

{
version
    {
    number 10
    }
prop The_Cube
    {
    geomCustom 
        { 
        ...
        } 
    }
prop The_Cube
    {
    name    The_Cube

External Name = The_Cube_1 (Internal Name = The_Cube)
External Name = The_Cube_2 (Internal Name = The_Cube_1)
External Name = The_Cube_3 (Internal Name = The_Cube_2)

And as a reminder here's the original cube results from the earlier post:

{
version
    {
    number 10
    }
prop TheCube
    {
    geomCustom 
        { 
        ...
        } 
    }
prop TheCube
    {
    name    TheCube

Started a new scene, deleted Andy, loaded 'TheCube.pp2' three times

External Name = TheCube_1 (Internal Name = TheCube)
External Name = TheCube_2 (Internal Name = TheCube 1)
External Name = TheCube_3 (Internal Name = TheCube 2)

It looks like it's simply whether or not there's an underscore in the the 'prop' (and/or 'name'*) field in the PP2 !

*I'd guess just the 'prop' field

---

The 3Dcheapskate (also available in DAZ and HiveWire3D flavours) occasionally posts sensible stuff. Usually by accident.
And it usually uses Poser 11, with units set to inches. Except when it's using Poser 6 or PP2014, or when its units are set to PNU.