Aligning barplot

All, Consider:

BagA <- c(-1000,10,10,10,10,10,10,
          10,20,20,20,20,20,20,30,
          30,40,40,50,60)


BagB <- c(10,20,30,30,40,40,50,50,
          50,50,50,50,60,60,60,60,
          60,60,60,1000)

layout(c(2,1))

barplot(table(BagB))
barplot(table(BagA))

At this point, I'd like to arrange the plots so that the 10-bars are
aligned, the 20-bars are aligned, etc. So, I started thinking, how do I
add an entry to a table? I tried:

tmp <- table(BagA)
tmp[8] <- 0
names(tmp)[8] <- "1000"

barplot(tmp)

But I got this error:

source('~/.active-rstudio-document')

Error in barplot.default(tmp) : 'height' must be a vector or a matrix

Makes me think I should not be telling my students to do:

barplot(table(BagA))

As it might give future troubles. 

1. What am I missing?

2. Can anyone propose an alternate strategy for aligning my tables?

Thanks

David Arnold
College of the Redwoods