Tracking multiple picks on the same team/side is an easy thing to do. In the example below, the first bet placed was on the Hawks at +4.
If you bet on them again at +4 with -109 juice, you could simply press the pencil icon to edit your bet and change the number of total units you have on them.
If you bet on them again at a different line, all you have to do is add the bet as you usually would, which would create two tickets on the same team. Below, you'll see that there's a ticket at +4 and +4.5.