There is a way i.e.

push @{ $directory{owner1} }, $value;
[download]

or

push @{ $directory{owner1}{0} }, $value;
[download]

if there actually is an intermediate hash with key "0" that holds the array (I'm not sure why you need the intermediate hash).

Updated: D'oh! Added missing commas in code samples (thanks hdb / choroba / davido !)