For cashback and rebates, there is double dipping or even triple dipping (UOB top up to grabpay card etc) For miles is there any double dipping hacks?

I don't think there is any air miles dipping hacks. It's mostly on cashback cards. I'm not sure about you but I'm on the cashback camp. I'll only use my miles card (OCBC 90N) for overseas purchase (then again, sometimes I'll just use Youtrip) or if my cashback card has been capped for the month.

There used to be the app mileslife, but it no longer exists and I think there isn't any other way to get double miles.