[R] Strange graphical pattern when using hist() function

[Humberto Mohr]

Running the following lines I got a strange plot from hist function:

x<-0:30
hist(x,breaks=31)

As you can see, the 0 value appears two times in the plot. 
The Y axis only presents 1 as the highest value when:

hist(x,breaks=62)

Nevertheless, it seems to have two bars between 0 and 1.

Could someone please explain to me why it is happening?

Many thanks in advance!