You could convert the UID of the laser to a string and use that as the tag. That would make the tag unique per instance, even for the same sound.
Just got round to trying this!
Doesn't seem to work as intended - here's my code:
And here's a demo demonstrating what's happening:
As you can hear, the first object starts playing okay - but when the second activates the sound isn't being positioned on to it and I can't seem to stop the sound.