From the docs,

  this function also takes a second optional array or hash reference parameter.

Not having played it myself, I can only conjecture that this should work:

  my @form_vals=(multival=>'val1', multival =>'val2', multival =>'val3
+');
  # or  , alternatively,
   my @form_vals=(single=>'Single Value',  multival=>[ 'a', 'list',  '
+of', 'values']);
  # Pass a ref to  @form_vals , when  you POST.
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