a 1 in 30 chance
That's just because your PRNG is only 15 bits: 

$ perl -e 'printf "%.3f%", 2**15/1e4'
3.277%

[download]
With a decent PRNG, you'd have a much lower chance of collisions.

In reply to Re^7: Generate a unique ID by Anonymous Monk
in thread Generate a unique ID by BrowserUk

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