caption overwritten in BQM

Hi all

I added the tool "assign captions" in one of my job in BQM. I set the 
flag "captions" , add my text "text2" and ensure the flag "cleanup and 
overwrite metada" is unset.
I selected a picture that already contain a text "text1", then run the job.
I was expecting to find in the caption : "Text1, Text2" but 
unfortunately, only "text2" was present. seems "Text1" has been erased

did I miss something ?

using DK8.8.0 on Win11

regards
frederic