Note that this works only for scalars (good enough for most purposes) - if its a list of object references and you want duplicates removed:

my %hash = map { $_ => $_ } @array;
# then...
my @unique_unordered = values %hash;
my @unique_ordered = grep {defined} map { delete $hash{$_} } @array;
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And for this to make sense the array elements must all be references to objects - if some elements are strings its possible for them to be equal to and overwrite a stringified reference.