Using stsadm to export subsite

I use stsadm to export one subsite. I get not one *.bak file, but over 800 files with name "subsite.bak", "subsite1.bak", "subsite2.bak" .... "subsite815.bak". every bak file is c.a. 25MB. Is it correct? How can I import the data in another site collection again?