Weddingbee boards

So the FI and I are hoping to make save-the-date coasters for our wedding and we are having a disagreement over whether each person/couple getting an STD should get one coaster or two. 

I say it's weird to send a couple (or a single person) only one coaster and that they should get a set of two.  Since one of the reasons I like this idea is that it's a practical save the date that people can use, I think that to maximize the practicalness, people should each get one. 

He says that nobody who has sent us a save the date has sent us each one (we've gotten like, four magnets) and that it would be weird to send two when only one is necessary to make sure that people actually save the date. 

So what says the hive? 

I'd say 4. Whenever I get favors of that nature and it's only one I always wonder what I'm going to do with just one...and it ends up in a drawer somewhere. If I had a set I would use it all the time!