Few months ago till date, there are instances of getting double/duplicate orders. I was thinking maybe the OneSignal thing or connectivity issues. I also recorded and showed to Stackcanyon the reason why double orders happened. some users claimed that during the checkout process there is a bit delayed for 3 seconds. they think their order didnt go through, that is why they press or tapping again. Stack advised me to remove the One Signal keys for the time being.. but I did not remove due to some reasons.