Do any other editing programs do what you describe above? Say Pro Tools or Adobe Audition?
In samplitude you can do this in the object editor. You put both stereo files onto two separate tracks. Each file is an object in Samplitude. You have to be in the context of a virtual project.
Then line up the beginning of both objects exactly with so that the drums sound synchronized. You have to use a cymbal sound, high hat or some event that stands out.
Then I go to the very end and slide the bottom object in time until some event at the very end lines up exactly. Then I determine how many samples the two files are out of sync. To do this you have to set the display to show samples and determine how many samples the object has shifted to get it to sync up at the end.
Then realign the objects at the beginning again, and finally enter a number into the object editor that tells the software how many samples to stretch the audio. (You do this to only one object and leave the other alone.)
Upon playback, the object with the time stretch value will be resampled to stay in sync with the other object.
I did this on a multitrack project recently and it worked perfectly.
Gordon