At some point in the past (2003?), "Learning Perl" was split in two, the second half being published as "Learning Perl Objects, References & Modules". That second half was then renamed "Intermediate Perl".
So I think a far comparison should show "Learning Perl" + "Intermediate Perl". As the width of both would still be less than that of the other book. :-)
Actually, Learning Perl never split. Intermediate Perl was the re-titled Learning Perl: Packages, References, and Modules. That book covered Perl 5 features that Learning Perl, a Perl 4 book, didn't.
I blog about Perl.