How to avoid "Cannot redeclare class" fatal error when two modules use the same class name in prestashop?
For example, I have module which declares and uses a helper class Foo. I install a new module which has a different helper class but with the same name Foo. So that causes "Cannot redeclare class" fatal error when I go to modules page. I cannot even uninstall that new module.
Well you'll have to edit one of those two modules and change its class declaration and every occurrence of that class in its other php files.
In the next version of Prestashop (1.7) the notion of namespaces will be introduced with the use of Symfony 2 Framework.