You can manage this using client variable. Create a client variable and set default value as a false. 

After calling the API set this client variable value as True. While calling API check if client variable value is false then call API.

Reset the client variable value when user go for the another payment.

Thanks

Vinod

I encountered the same problem. Tried to do everything according to the recommendations of the previous commenter, but the problem remains unsolved. Maybe I'm doing something wrong?

Hey,

I think you should try to create flag attribute(Boolean) in entity, whenever you come back to application set that flag to true and then call API. 

After that when you will refresh the payment Successful page check for flag in entity if it is true then don't call API else call API.

Thanks

Yogesh