Missing data in usps dataset

[CFCTgithub]

The data labeled as "6" and "7" have each been overwritten with the data labeled as "5" in the usps dataset.

data(usps)
five_idx <- 1 # any integer from 1 to 1100
opar <- par(no.readonly=TRUE, mfrow=c(1,3), pty="s")
image(t(matrix(usps$data[4400 + five_idx,],nrow=16)[16:1,])) 
image(t(matrix(usps$data[5500 + five_idx,],nrow=16)[16:1,])) 
image(t(matrix(usps$data[6600 + five_idx,],nrow=16)[16:1,])) 
par(opar)