Webhook responding more "PAYMENT.CAPTURE.COMPLETED" than the number of "CHECKOUT.ORDER.APPROVED"

[LeonarAung]

WebHook responding more "PAYMENT.CAPTURE.COMPLETED" events than the number of "CHECKOUT.ORDER.APPROVED" event.
5 Orders is making "33 PAYMENT.CAPTURE.COMPLETED" events from various locations of "appengine" .

Here is the "PAYMENT.CAPTURE.COMPLETED" webHook events recorded in database. I found ungenerated order_id too in the list . 

I just made 5 orders. This project is still in development and using sandbox app.

I am new Paypal Developer and is this condition normal ?  Thank you for your help.