Which version of Music Maker are you using? The current version of MM2022 is 30.0.4.44.
What do you mean by overwrite? The audio of track 1 changes to be the audio of track 2? Does the object name also change?
Do you understand that when you play back, all tracks play back at the same time, so if both audio objects start at 0 on the timeline, you'll hear both played together, not separately?