This is only an example, but the concept may help you.
Let's say we want do sample ten numbers randomly (and uniquely) from a
distribution of one to one hundred.
Enter the numbers one to one hundred in a column. In the next column enter
=RAND() and copy down. Sort by the second column; this will jumble the
first column. Just take the first ten entries in the first column. They
will be randomly picked from the distribution with no repeats.
Hope this helps