What should I do in this situation that purchase by different accounts of us?

See IAP FAQ TN2413 Error Messages / Cannot connect to iTunes Store

If you continue to have specific issues, say w/sale in CN, you might need to use one of your Member Center DTS support tickets to see if they can help in that example.

Good luck.

Tags: echo,to,followup T#IA: 45786a, attn. V.T.

issue 1) ".....transaction StateFailed with reason “can not connect to iTunes Store”, then I will note to user that purchase failed. But, paymentQueue update a transaction StatePurchased later."

When a user initiates an IAP if their credit crad information is not current then the App Store will ask them to update the credit crad information. After they do that the App Store will ask if they want to complete the IAP. If they say "YES" then StoreKit will send to the app two transactions. The first will be "Failed". That will be followed immediately by a "Purchased" transaction. Perhaps this is what you are seeing.

issue 2) At this moment, I can not be sure witch order can match this purchased transaction. Usually, I use applicationUsername

The purchase will come into updatedTransactions. You can get all the information you need from updatedTransactions or the receipt. If you are relying on applicationUsername you are most likely doing something incorrect. That is not the purpose of applicationUsername.