It happens all the time. I've tried to talk people out of donating stuff many times in the past with very little luck. They all think their relatives stuff was gonna be proudly displayed through the next decade or two.
In the case of the guy with the German items, he wanted them to come to us and get displayed. As for the rest, the likelihood of any of them getting displayed at the previous museum was slim to none, so at least we will display them with the families info in most cases at our museum. Its quite common for museums to do transfers or de-accession items. As a side note, why talk people out of donating? Most reputable museums have good intentions and the items will go into rotation. They could sell or give to a collector,and that person will likely take care of the item, but for how long? He or she will inevitably die and then what? Museums are handed down through board members, employee's, etc... So, while it could get traded or sold, it could just as likely be preserved for 100 years or more. Scott