prasadbabu,
I think you have misunderstood though it is not your fault and I might be the one that is wrong. rsriram said unique elements but meant unique indices judging by the rest of the node. In other words, by repeating the random number selection, the same index was appearing multiple times. While your updated use of the Data::Random module gets the job done, the %unique is not needed. Update: Your second update corrects all the problems and this is a valid solution.

Several ways to do this that involve changing the original array are to use List::Util's shuffle() as davorg has suggested or use splice to pull out elements randomly. Alternatively, a parrallel array of indices allows the original array to remain intact.

my (@index, @rand);
@index = 0 .. $#array;
push @rand, splice(@index, rand @index, 1) for 1 .. 10;
print "@array[@rand]\n";
# untested
[download]

Update: I added a couple of alternatives that do not leave the original array intact. Additionally, I need to point out that your use of Data::Random can be terribly runtime inefficient. See my update in this node for details. The alternatives consume more memory (trading space for time). I also originally incorrectly thought that the module was returning the set in the original order by default but it isn't.