Comment 3 for bug 1461739

That would be my suggestion as well. Just copy the whole button bar.

Beware variables in the template that affect whether a drop-down is open. For example:

is-open="gridColumnPickerIsOpen"

The secondary/copied drop-down would need a new variable, is-open="gridColumnPickerIsOpen2", or some such.

To reduce code duplication, I also suggest moving the button bar TT2 code out to its own .tt2 file, which is INCLUDE'd into into t_autogrid.tt2. That way we can INCLUDE it twice. With this, we'll need to pass a variable down with the INCLUDE statement to tell the button bar TT2 whether it's the top bar or the bottom bar, so it can modify local variables (see is-open example above) as needed.