Double sorting in firefox

It's cool that I can sort one column of numbers and then sort another column which has duplicate values and the first column is still sorted, like:
1 1
2 1
3 1
1 2
2 2
3 2
etc.

This works great in IE, worked in FF1.0.2, but is now broken in Firefox 1.0.3. I searched this forum and couldn't find solutions. Hoping someone could look into that one.