Although the objects, entities and brushwork have been move further up the wall to make it easier to see the steam jet effect with two jets, it's the same brushwork setup as shown in the previous section of this tutorial discussing the use of just one steam jet..
Brushwork and Item placement
The 2 target_smokes' are placed in the same location to give the effect of 2 streams of steam using the same setup as before.
Entity setup in the "Inspector" for multiple Steam effects

Connecting the target_smokes to the info_nulls
The ingame results of this one are interesting and display one of the various 'issues' that seem to happen when trying to use multiple entities in this way (these 'issues' are separate from the ones that happen running under MP where the smoke appears to only go straight up or down), note the angle of the lower smoke, it's much shallower than shown in the ineditor setup screenshot above.
note also that although the entities set up ineditor is approximately the same the results are very different becasue of the variation based on distance between the info_notnull target and the shorter 'delay' key/value.
In game shot of the two steam jets
There does appear to be a 'bug' with approach though when trying to have more than one jet running at the same time from the same location. The angle on the lower jet doesn't match what's seen ingame (less shallow angle) so there are some limits to what can be done.
It must be noted thought this only appears to apply to entities being active at the same time so it should be possible to have several in the same place in the editor and spawn/hide them according to the events needed without this error.