I was playing slardar yesterday with gondar in my team. when i amplified a tracked hero the track buff dispelled. Why?
These spells are likely based off the same WC3 spell (which one I don't know, exactly).
Many spells that have the same base will not stack with each other for legacy reasons. These seem to slowly be in the process of being weaned out as they're antiquated and basically just rote memorization, but for now they remain.