If he's using Flyweight intentionally, then the overwriting of instance data is to be expected. This is not what he wants however. The point of the Flyweight is to enable the quick flow of data through a standard framework. But he appears simply to want standard inheritance, for which package lexicals will not do for more than one instance.

Update: D'oh! so sub phrase : lvalue { $phrase{shift}; } means that the shifted value is the memory address of the thingy and since it's an lvalue that is assigned the unique instance data. Ergo, my $opinion = ('cool!' && 'eewww!').