ICS Array in array without repeating elements

Summary

I have a query that returns some values. But i only need unique elements out of them

Content

I have a sql that gives the output as per image screenshot. 

And current response that we get

Data : [

“class” : “English”,

 “alumni” : [ {“name” : “John” } , {“name” : “John” },{“name” : “Eric” }]

But we only want distinct valued response like below and manipulation to be done in ICS(mapper)

Data : [

“class” : “English”,

“alumni” : [ {“name” : “John” }, {“name” : “Eric” }] ]

Please suggest on doing this.