How to create object instances with unique properties in Blender? Is it possible in Blender to create several instances of an object (Alt+D) and then to change some properties for one of them? (i.e. creating an instance with unique properties)
In particular, I am interested in created instances of "Text" object  with different text in them.
Alt + D creates a linked duplicate. You could just duplicate using Shift + D. Then each duplicate has its own copy of the properties and modifications are just to that object.

Alternately if you already have the linked duplicates (and only want have unique text), then go to one that you want to have a unique text and click the number button (number of users of this property). This creates a new data block, which you can then have different text (and text format) assigned to it.