Nah, we have 2 sets and only one is missing the box kite. The other is complete, so no need for duplicate material. Part of our problem is that many people don't know how, or when to say no to a donation. Because of that, we have enough naviagtional sextants to start a navigator school! I kid you not, we have at least a dozen, all in great shape.
We do exchange some items, but each museum has a slightly different focus and some museums are not interested in partin with anything. Kind of a strange situation.