How to change a filter handler of the view? I have created a nice Filter Handler for my View, and I set it up using hook_views_data_alter.

Does this mean that this will ALWAYS be the Filter Handler for this particular field? What if I want a different Filter Handler later, in a different view?

How can I specifically say "Only use the X handler on page X?"

For posterity, I thought I'd outline more of what I was trying to accomplish here:

I have "Friends" page and a "Content" page. On the "Content" page, I wanted to be able to filter by "Content posted by my friends." However, on the "Friends" page I want to filter by "Users in my Groups." Both of these query on the user.uid field, so it was making the filters the same, even though I wanted totally different logic for the two views.
I always take the following approach: Copy the existing views_data code via php:

// Copy the existing definition.
$data['table']['field_special'] = $data['table']['field'];
// Force the real field, so views still consider it as a different field in SQL.
$data['table']['field_special']['real field'] = 'field';
// Set a special handler.
$data['table']['field_special']['field']['handler'] = 'foo_handler_field_...';


This allows you to easy reuse the custom handler if needed, but at the same time not conflict with existing views.

In contrast to the approach of berliner (which certainly works) this does not add any runtime code execution, which adds potential bugs. This approach just uses basically configuration.