Several other monks have been suggesting ways to handle this that end up modifying @array. If your part of the program receives a reference to @array, you can use the dclone method from the core module Storable to copy the array and then mangle the copy however you want.

Adapted from the Storable POD:

use Storable qw(dclone);
# ...
my $arrayref = dclone($provided_arrayref);
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As long as @array is small enough to copy, this should be very efficient; Storable is an XS module.