How can we correlate a specific value which has same boundaries as some other values?

We are facing some challenges while trying to correlate one value.
We have a server response below:
Name","store":[["","<none>"],["Person:XYZ","Karen Egertson"],["Person:ABC","Robert Farley"]],
From here we want to capture value “ABC” with “LB=["Person:” & “RB=","Robert Farley"]],”.
But it is taking the first occurrence of the LB and then picking up the value till RB. So the parameter value it is fetching is like XYZ","Karen Egertson"],["Person:ABC and we are not able to find out any unique boundary.
Please provide us a complete solution.