CAD tip # 14285:

Download the app from Download, load it into your AutoCAD with APPLOAD and start it by typing the SELDUPBLK command.

You can specify the block to be compared by pointing to or typing a name, a list of names, or a name mask wildcard. You can specify the list of attributes to be compared and their specified values for comparison by simply pointing to them or again by using a name, list, or mask. When you enter an attribute name, you also manually specify the attribute value to be searched for - again, you can use a list or mask.

For match detection, you can choose exact match, case-insensitive match (a=A), or broad accent-independent match (hachecks, umlauts, ß, etc.), or substring match (e.g. first 4 characters).

Found duplicate blocks are pre-selected by node editing - so you can easily move them to another layer, change their color, etc.

See video examples:

Blind select:

You can add a conversion table for the broad match - e.g. to add V=5, VII=7, X=10 - using the LISP variable: