How do you deal with scenarios when the same user has 2 browser windows of the extension open?

[BarryCarlyon]

@Dist

Each useBits transaction has a single id, regardless of how many tabs that receipt is sent to. I could be sent a thousand to my EBS, 1 id = 1 transaction = 1 increase in ‘tokens’ by the SKU used.

This doesn’t solve OP’s problem.

The problem being EBS gets two Transactions at the same time and is processing transaction B whilst Transaction A is being written to the database. (Where transaction B is a duplicate of Transaction A)

You’ve just moved the problem