remove duplicate elements from array?

Question

I'm not sure solution is Question:

{
A: 'AA',
B: 'AB',
C: 'AC',
D: 'AD'
},
{
A: 'AA'
B: 'AB',
C: 'AX',
D: 'AY'
},
{
A: 'AA',
B: 'AC',
C: 'AX',
D: 'AY'
},
{
A: 'AB',
B: 'AC',
C: 'AX',
D: 'AY'
}

and He want result is:

{
A: 'AA',
B: 'AB',
C: 'AC',
D: 'AD'
},
{
A: ''
B: '',
C: 'AX',
D: 'AY'
},
{
A: '',
B: 'AC',
C: 'AX',
D: 'AY'
},
{
A: 'AB',
B: 'AC',
C: 'AX',
D: 'AY'
}

I'm sorry I want to know how to do it, Thank you.