Hi Ronald,
These are the last 10 versions of an LO. It's kind of a poor mans version control. It has saved people a lot of work in the past.
In our install, which has about 15Gb in USER-FILES, these particular files occupy 0.5 Gb, which is less than 3.5 %.
We believe that to be a usefull trade-off
It would be nice (and I will put that on the feature request list) to be able to control the number of copies through the mangement page, or replace this with more sophisticated version management.