As you can see the Conjurer has no longer the keyword "Durable". Since the effect is bound to the keyword, it is impossible to have durable effect without the durable keyword. You probably just got unlucky. Since it's a common card and you most probably got more common cards in hand, the chances of getting Conjurer are quite high.
Becuase of anti-flood protection chances of getting card that you already have in hand is reduced. Cards like Conjurer kind of ignore this rule. It's because new card is drawn before the card effect happens.
So in short it happens this way:
1. new card is drawn
2. card effect happens
So the anti-flood cannot react to the fact that there is already another Conjurer in hand, becuase new card is already drawn.
New card should be drawn after the card effect. This way, it could react to the fact that there is already a Conjurer in hand, thus reducing the chances of getting another Conjurer.