How to identify total no. of unique activities reported to IATI?

Dear IATI community,
I’m performing an analysis of the IATI dataset reported by 23 EU publishers, and I was wondering if there is a way how to extract full list of UNIQUE iati-identifiers (without duplicates) in order to identify a total no. of UNIQUE activities reported to IATI.

I’ve noticed that IATI dashboard provides an information how many times iati-identifier (unique activity ID) has been used. However, as the same iati-identifier can appear multiple times in different XML files, the IATI dashboard just sums up all iati-identifiers used in the publisher’s dataset and does not show a total no. of unique iati-activities reported.

Giving Romanian dataset as an example,
Romanian ODA 2014 - 2016 XML contains 670 unique activities
Romanian ODA 2014-2015 XML contains 430 unique activities,
however iati-identifier XM-DAC-77-2014000001 appears in both XML. How can I therefore identify a total number of unique activities reported in the whole Romanian dataset?

I would really appreciate any comments or suggestions.