wrong statistics/results from filtering with publication type

Filter:
Rights: Open Access
Publication year: 2008
Language: english
Up to this step, results are 293997 publications

add: pre-print (5141) 

results: 29288 publications, all from OpenAIRE, 0 from CORE.

BUT

29288 exceeds the 5141 number of pre-print
and pre-print gets the number 2251