[R] post - plotting lines in a divided graphic device

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Hi all,
I have a graphic device divided in 2 areas for a plot.
Is it possible to add lines or points in the first plot after the last 
one  have been set, without plotting all the data again ?

Example
par(mfrow(2,1))
plot(1)
plot(2)
lines(c(1,2)) # should be visible in the first plot

Thanks for help.
Greetings