Importing new solution version without any changes to the ribbon button and maintaining customisations is acting like overwriting customisation in regards to the ribbon button existing customisations.

This should only happen when you overwrite customisations and not when you maintain customisations, as it overwriting button customisation in a parent solution when you import a child solution. This is causing to have to import every solution each time there is an update in one of the solutions.

Please see case number: 120021824000177