You can call the function with parameters. Just add "S1L1" or "S1L2" as parameter. Have in mind that parameters (you can add many) are a list. All lists in C2 are zero based.
Now, in the On function use two conditions
System > Compared 2 values ...
with ... function.param(0) = "S1L1"
pick those with touch and do stuff on them
System > Compared 2 values ...
with ... function.param(0) = "S1L2"
pick the others with touch
Manual > Expression Param
Retrieve a parameter passed to a function call by its zero-based index. For example, Function.Param(0) returns the value of the first parameter.
You know wich one is dragged when you give them an instance variable, say, lets name it Level. Give it the value "S1L1" or "S1L2" in the layout.
This way you can call the function with as parameter ... Object.Level (no if/thens, straight & easy)