spuunmux extracts vobsub subtitle with wrong time stamp

  spuunmux could extract these subtitles out, but have wrong timestamp
if the vobsub subtitle file contains more than one subtitle. the first
extracted subtitle is all right but the subsequent extracted subtitles
seems to have continued timestamp, for example, suppose the first
extracted subtitle is one hour long, then the timestamp of the second
extracted subtitle begins from one hour. any one know how to fix this?

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/