How can I add two identical (but with different data_base) ggplot into one graphic?

See the code for the plots below:

**PLOT1:**

ggplot(ipw_monthly_out2, aes(x = month, y = effect)) +

geom_line() +

geom_point(aes(x = month, y = sig), shape = 18, size = 3) +

geom_ribbon(aes(ymin = cil, ymax = cih), alpha=0.3) +

theme_bw(base_size = 20) +

xlab("Months after program start") +

ylab("Effect on exit rate highedu (IPW)") +

geom_hline(yintercept = 0, linetype="dashed")

**PLOT2:**

ggplot(ipw_monthly_out2_l, aes(x = month, y = effect)) +

geom_line() +

geom_point(aes(x = month, y = sig), shape = 18, size = 3) +

geom_ribbon(aes(ymin = cil, ymax = cih), alpha=0.3) +

theme_bw(base_size = 20) +

xlab("Months after program start") +

ylab("Effect on exit rate highedu (IPW)") +

geom_hline(yintercept = 0, linetype="dashed")

**Please, can somebody help, I have tried for hours:(**