Ref. No. 2245/44-2381
In the name of Allah the most Gracious the most Merciful
The answer to your question is as follows:
Even if the payment is made without informing the owner, the payment will be valid. And hopefully the sin will be removed. However, you should say to the shopkeeper, “If I have done anything wrong with you accidentally, please forgive me”. So in this way you will get his pardon.
And Allah knows best
Darul Ifta
Darul Uloom Waqf Deoband