@jim said:
Is it a possibility that extensions written independently by different authors inadvertently use the same Extension name?
Of course they can, if they choose a simple name like "Cylinder" and do not set a version string, or everyone starts out with "1.0.0".. then yes they can conflict.
Authors should use unique names, like: "Foltz: Cylinder", and use a proper version string.
@unknownuser said:
Would that mean that only the last loaded extension would be available?
Sketchup decides whether to load (or not to load,) extensions, based upon a concatination of the name and version string. (Check the registry and you'll see what I mean.)