If Cursed Wombat leaves the battlefield and returns to the battlefield in the same turn, or if one Cursed Wombat leaves and another Cursed Wombat appears, the ability granted by the old one is different than the ability granted by the new one. This means that a permanent that already got an additional +1/+1 counter from the previous granted triggered ability could get another additional +1/+1 counter from the new granted triggered ability if more +1/+1 counters are put on it during that turn.