Did you order one for each guest? If so, that would also account for many leftovers. If my husband and I attended, we would only take one favor like this home no matter how much we liked it. We would assume that was your intention unless there were one at each plate or something, and even then we'd probably only take one.
Even if you only had one for each couple and one for each single, there'd be extras even if everyone wanted them. If a family of 2 parents and 3 children came, they probably wouldn't want to take home 4 sugar dispensers.