The DAW I use lets you do loop recording with punchin/out points and it just stacks the clips, however, it only plays the most recently recorded clip or whichever clip you decide is 'on top'.

Handy for recording a difficult section with multiple takes without all the re-arming and record button pushing. My little vocal 'booth' is about 5 feet from my keyboard and rather than trot back and forth between booth and keyboard, if I know I'm going to record several takes of a section, I can set it up for loop recording and go to town, then keep the take(s) I like best. In order to play them simultaneously, I will then usually drag the individual clips to different tracks (great technique for double-tracking, btw).