In Terminator: The Sarah Connor Chronicles season 2 Episode 21 (Adam Raised a Cain), John connor, Sara Connor, Derek Reese and Cameron come to Catherine Weaver's building to save Savannah Weaver. In this rescue mission Derek Reese is killed by a Terminator. This incident happens in the year 2007.
So in last episode of season 2 John Connor and Catherine Weaver went to the future and then John found and met "Derek Reese" with the resistance army. So my question is, if Derek Reese died in 2007, how is it possible that he is alive in the future?
All these incidents are happening on same time line and the same earth.