WordPress MU

I have two WordPress installations on my site arranged in separate directories, like this:

/public_html/wp-blog1/
/public_html/wp-blog2/

Seems to be working okay, except for when I use the get_posts() template tag.

If I try to do this in wp-blog2:

$arg = "numberposts=50"
$posts = get_posts($arg);
foreach($posts as $post) : setup_postdata($post);

...
<?php endforeach; ?>

I get a listing of posts in wp-blog1 (!)

Is there any way to specify which database get_posts() gets from?

Why am I having this problem?

How do I use get_posts() with two WP installations?

Thanks

Are you using WP or WPMU? Do the two installations share a database?

I guess I'm using WPMB - multiple blogs. There's normally only one user. The reason I'm using multiple databases is for scalability. I want to keep the size of my databases as small as possible. When a database reaches a a few hundred meg, I tear off a category and put it in it's own db.

So I guess I've posted in the wrong forum.

In any case, I think I figured out what was going on (long story).