Randomly generate 4 or 5 digit Unique Codes in Subsequent Runs of the Script

I have a requirement to Generate 10 4 or 5 Digit unique numbers. I can do that using Python/Perl, but the same script is going to run everyday to generate 10 random numbers. So I don't want them to repeat. If I generate them randomly then there is a probability that they will repeat.

Please suggest.