You message wasn't precising that you hadn't placed erratic orders before.
Yeah if you really placed 1 order and it got there twice, that's new.
Perhaps it has happened before and we didn't notice it, assuming it was one of the erratic orders that passed. Hard to know, since it's rare for the first order placement to succeed.
I agree, it is rare that orders directly succeed in being placed in a single call.
We have a very specific log, and in a few cases there were orders which went through without having to use additional calls, still the orders were placed twice. So, we are very sure that double placement was not caused by additional calls for those orders, but that double placement was caused by an error on Kraken's side. Atm, it seems though that we do not have this issue anymore today.