# Doesn't delete anything else in the %{$data{$name}}
$data{$name}{$key} = $keyvalue;

# Erases everything else in the %{$data{$name}}.
%{$data{$name}} = ( $key => $keyvalue );
[download]

It's bad to actually create variable dynamically. (You can see the reason for that here.) That's why I'm not creating a variable named %hash1. Rather, I created %data which hold %hash1 and any other hashes you wish to create dynamically.