You can use the 'Edit → Find/Replace...' dialog (Ctrl + F) to select objects with similar attributes and styles. It requires a bit of knowledge about the underlying SVG and XML code, but is very powerful.
Just switch the 'Search in' setting from 'Text' to 'Properties' and enter some value they all have in common. It might be helpful to use the 'Edit → XML-Editor...' to inspect the attributes of one of them and find something you can search for. If they all have the same path-data, for example, then you can copy-and-paste a short snippet from the
d attribute into the search-box and click the 'Find' button.
There are also more search settings in the expandable 'Options' section to narrow down the results.