Welcoming Vampire can trigger more than once and/or for each creature entering rather than once per batch of creatures entering

I had a [[Welcoming Vampire]] in play and created a bunch of tokens at once with [[Elenda's Hierophant]]. Somehow, I got a Welcoming Vampire trigger for each token, when it should have only triggered once for multiple creatures entering the battlefield at the same time (and also should've only been able to trigger once in the first place)