in reply to How do I double up elements within an array?

And yet another way... 
my @array1=(1,33,45,66);
my @newarray = sort { $a <=> $b } ( @array1 ) x 2;

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Or, if you don't care about the order, as long as similar elements are adjacent (although it doesn't make any difference for your sample data): 

my @array1=(1,33,45,66);
my @newarray = sort +( @array1 ) x 2;

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Unless I state otherwise, all my code runs with strict and warnings

In Section Seekers of Perl Wisdom