There are, of course, few warranties in the software world, and collisions in 128-bit space are possible,
but very remote. I'm just pointing out that they're less remote (by many orders of magnitude) if you are
assigning values using two different algorithms (the examples you referenced use the same algorithm
that ArcGIS uses, so they're not likely to conflict).
If this is the only way to meet your requirement, so be it. But I do urge caution (and a UNIQUE index
and robust error handling during assignment)
- V