Yet More Guilt

So where is all this guilt coming from? It's not like I was raised Catholic or anything! I wonder sometimes if it's the right emotion, or if guilt is just the closest match for these feelings.
Here's a little guilt story for you.
Before Christmas, I was doing some clearing and decluttering in the basement. I had bins of toys, gathered from various parts of the house. I went through them, consolidating and purging. I managed to fill two paper grocery sacks with toys, books, etc that either I didn't want the kids to play with (i.e. noisy toys, broken toys) or ones they'd themselves identified as ones that could be given away. Younger DD had two identical soft foam number puzzles, both gifts from the same person. Why two were given, I don't know. No matter, she had two. I thought, "I can give one of those away, easy, no guilt no problem because there are two". Sounds fine, right? Well, days later, younger DD was playing with the remaining one, and older DD wanted to also. Older pointed out that there were two of them (oh no, I thought, she remembers!) and so they could each have one to play with. They bickered some more, and older DD continued talking about the two puzzles. I felt just awful! I had given away something they remembered and talked about! How could I have done that? I could never do it again, making decisions for them about their things! How would I feel?

And so on and so on. Torturing myself over and over.
For a foam puzzle that had been ignored for months before that day.
This is an insidious disease, painful and frustrating.