No...

When you merge topics, in flatmode the order that the topic is shown is in the original posting order.

It's not that topic A is appended to topic B, they are merged, as in mixed together if both topics ran simultaniously.

The bug repored is about when you merge topic A to topic B, topic B's last post date/time/subject is not updated to reflect the latest topic in that topic.

[Linked Image from siemons.org]