I grew up going to weddings with registrys so long they had to have either more than one gift per person or buy the vast majority of items there themselves. Likewise, I've seen couples with multiple of the same gift, sometimes with cheap variants of an item that they were really looking forward to.
My future sister-in-law, however, decided to not have a Registry at all. She and her husband instead asked for money at the wedding. It seems like an easier option, but I feel a bit awkward asking for money when my guests will already be traveling in order to attend.