I consider it a bug that Velen, Leader of the Exiled, when copying the deathrattle of Adaptive Amalgam, shuffles a copy of Adaptive Amalgam instead of his own copy. Archdruid of Thorns works correctly with Adaptive Amalgam, but Velen does not.
Those cards do not have the same text
Archdruid of Thorns gains a copy of the deathrattle, which means it’s now its own deathrattle.
Velen does not gain a copy of the deathrattle, he triggers the deathrattle of another minion
In the latest Saronite Chain Gang card balance, the battle cry was changed from “Summons a copy of this minion” to “Summons a Saronite Chain Gang”. At Velen’s death, this effect applied specifically to Velen and not to the convict, summoning Velen endlessly, then the map was fixed. If the Draenei Convict effect applied to Velen, then the Adaptive Amalgam effect should apply specifically to Velen.
Velen’s text is inconsistent as he repeats battlecries and triggers deathrattles, he doesn’t trigger both
Cards that repeat battlecries are the emitters of the battlecries, so they take the effect of it
Velen was supposed to be copied by the Saronite battlecry, his text is just simplified which made it inconsistent