In Pixiv random delivery, QQ sendMsg can return a success event and still time out while waiting for the later message update callback. Treating that as an ordinary failure leaves the illustration out of the sent record, so a later random job may send the same work again.
The update recognizes this case separately: when the error contains retcode=1200, a sendMsg timeout, and a success-event fragment, the plugin records the illustration as accepted for delivery. The log still describes the timeout, while duplicate random recommendations are reduced.