Yes. You can track multiple Jobs. A Job can be a totally different employer or just a different thing you do at the same place. Note if you want to track different hourly wages you'll want to do that in Positions.
Click the More tab
Select the Settings item
In the "About your work" section click the Jobs item.
This will open a new page where you can add Jobs.
Click the Add button.
Enter the Job name.
Select the Start of Week for that job. When you select this and set the filter to this job on the History or Averages charts, it'll reset the charts to start with this day.
Turn on Color and select a unique color for this job if you want to display a small dot on the Calendar indicating that the job was entered that day.
Click Save.
Once you add Jobs you'll be able to Filter for them on all pages. Look for the Filter icon on the top right of each screen. This will change the view to only show what's filtered.