How can I add two types of bolts with different properties in Unwedge?

First define two bolt properties for the two different bolts.  Use the Add button to add a different bolt type.  


Add bolt types 


After you have defined the two different bolt properties, add two bolt patterns, one for each type of bolt.  In the bolt pattern dialog, select the bolt properties type in the upper left corner.  Add the two different patterns.


Select bolt type with drop-down menu in Add Bolt Pattern dialog