I think that UIMAUpdateRequestProcessor should have a parameter to avoid duplicate values on the updated field.
A typical use case is:
If you are using DictionaryAnnotator and there is a term that matches more than once it will be added two times in the mapped field. I think that we should add a parameter to avoid inserting duplicates as we are not preserving information on the position of the annotation.
What do you think about it? I've already implemented this for branch 3x I'm writing some tests and I will submit a patch.