quantmod: overlaying time series bar charts

Hello,
I was wondering if there is an easy way of overlaying two bar charts
using quantmod?
Here is what I am trying to do:

chartSeries(ts1, type = "bars", show.grid = TRUE, up.col = "green",
dn.col = "green")
chartSeries(ts2, type = "bars", show.grid = TRUE, up.col = "red",
dn.col = "red")

But have ts2 show in the same plot frame or if that does not work have
it show in a frame below the first one.

Regards,
Sebastian