simple bug/compat question

[Linda Walsh]

Am running an older bash version and this may be fixed (assuming it
is a bug and I'm not confused...:-))

bash version = 3.2.39(20)

This works:
1)      if [  -n ""  -a 2 -gt 1 ] ; then echo one;fi

This does not:
2)      if [[  -n ""  -a 2 -gt 1 ]] ; then echo one;fi



Shouldn't 2 work equally well as 1?

(original test on "$1":
        -n "$1" -a "$1" -gt 0
)