I have my amex account connected to Monzo and it started showing the same transaction twice, one of them as pending. I have this for different merchants where I payed using Apple Pay. Neither the amex app or the apple wallet show these transactions as duplicated, so it looks like a bug in the Monzo app
Hi @Ariana1 & welcome 
I’ve had the same duplicated Amex transaction experience on Android - but only occasionally. And after 2-3 days, the duplication in the 
app disappears.
Deffo a 
though.
.