Both options are possible.
The simplest option is to just have a 2nd job containing the second set of targets & blackbox URL.
However you can combine the two into a single job by encoding the
blackbox URL within the targets. For example set the targets to
blackbox1:target1, blackbox1:target2, blackbox2:target3. You can
then split using regexes to set the bit before the colon to
__param_target and the bit after to __address__ (with the :9115
suffix).
-- Stuart Clark