How do we find out User information form Apple server notifications?

How do we find out User information from Apple server notifications?

I have created a user and purchased an In app product from Apple . I have received a INITIALBUY notification from the App store.
Apple ID : xxxx@gmail.com
User : ABC (User id :111)
The JSON receipt contains the following fields.
"latestreceiptinfo": {
"transactionid": "1000000657540200",
"originaltransactionid": "1000000657537943",
"quantity": "1",
"subscriptiongroupidentifier": "20623048",
"isinintroofferperiod": "false",
"purchasedatepst": "2020-04-27 23:41:05 America/LosAngeles",
"istrialperiod": "false",
"expiresdateformattedpst": "2020-04-27 23:46:05 America/LosAngeles",
"productid": "com.***.iap1.5",
"weborderlineitemid": "1000000052078939",
"uniquevendoridentifier": "xxxxxx-xxxxxxx"
},

I have created one more user  from the same Apple id and purchased the same product.
Apple ID : xxxx@gmail.com
User : XYZ (User id :222)
  "latestreceiptinfo": {
"transactionid": "1000000657540202",
"originaltransactionid": "1000000657537943",  
 "productid": "com.***.iap1.5",
"weborderlineitemid": "1000000052078942",
"uniquevendoridentifier": "xxxxxx-xxxxxxx"
},  

I have store user information based on productid- 
originaltransaction_id =>user 

xxxx@gmail.com -  com.***.iap1.5 - 1000000657537943 -ABC

xxxx@gmail.com - com.***.iap1.5 - 
1000000657537943 -XYZ
In this case I could not track the user information.Duplication will come

From the same Apple id ,2 different users buy the same product Apple will give the same original transaction Id.

Is there any other field to differentiate transactions to find users ?
Is there any option to include User name on JSON server notification from App store.