Your question is confusing. If you are referring to importing a bank statement, each receipt will be separate. If you are referring to posting a single receipt against multiple receivables, that is not importing.
If your issue is that the customer has paid multiple receivables at once, you can leave the sales invoice selection blank. Manager will allocate the receipt automatically to unpaid sales invoices, oldest due dates first. This is explained in the Guide about recording receipts.
well i receive one receipt from our bank which totaled the monthly client direct debit.
then i have to create over 500 Accounts receivable with the same receipt + client name and amount.
There is no easy way to do this other than manually entering it.
However, perhaps there could be a button on Customer Summary report which could copy closing balance for each customer into new receipt which could get you very close to the final result.
Another way is to simply create individual receipt for each customer as a separate transaction and then one payment transaction to record processing fees so the total of your bank account will be the same as on your bank statement.