Reference to What is Not

Bill is discussing reference to what is not with Lukas Novak.  In a comment he says,

It now strikes me that what you and I mean by 'nonexistent object' is different. What I mean is an INDIVIDUAL that actually has properties, but does not exist or have any mode of being. The example I have been employing is THE golden mountain. It ACTUALLY, not merely possibly, has exactly two properties, being a mountain and being made of gold. Just those two properties and no properties entailed by them. There can only be one such item; hence THE GM.

But why must there be just one such item?  Are we not in the same domain as Max Black's iron spheres of which there are two?  If Bill insists on just one such individual that has exactly the two properties then I think he must be talking about the description 'is a mountain and is golden'.  The order of the properties is not significant.  But of course, a description has properties in a way different from the way a concrete object has its properties.  We are in the realm of Zaltaian abstract objects.