Two datasets on the same frame using RooFit?

Hi all,

I am using RooFIT to do the following:

(1) I have two datasets (the variable is the Z mass):
one from real data and the other from simulated data
each having different total number of events.

(2) I want to fit each of the datasets with a PDF (crystal ball) separately
and want to plot it on the same frame so that I can compare both the fits
and see if there is any shift in the Z peak.

I know how to plot and fit one dataset.
is it possible to plot both the dataset points (which have different number of entries)
and there fits on the same frame so that i can compare the Z peak?

Thanks for help,