Multiple multiples...

Having used DT for several weeks now, I figured out that most of the files in the “files” subfolder appear in multiples (3-5 times!). They have suffixes like -1-1, -1-2, 2-1 etc.

I cannot recognise any system behind the unintentional creation of multiples: what am I doing wrong? I’ve deleted the manually and cut the size of the db into 1/3rd.

Anyone has seen this before? Any hint?