I don't actually know what Sum of all tables is, but Installatron installs Joomla two different ways.
If you do an install with the default settings it installs like this:
. Asks the control panel to create a database.
. Edits the .sql files to use the generated prefix.
. Imports the .sql file that creates the tables using a standard PHP mysql import.
If you do an install with the "I want to import a Migrator file" option it installs like this:
. Asks the control panel to create a database.
. Loads Joomla's own install script as an "External Task" step, and this Joomla script creates the tables.
The method of creating the database and importing the .sql tables could possibly give varying results.
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If it's causing any sort of problem you might be better off opening a ticket:
https://secure.liquenox.com/ticketsRowan.