I did a little test to see what happens when you run two timelines at the same time, and both are trying to animate the same property in a conflicting way. I started them with a button thusly:
It seems to me that where there was a conflict, it gave priority to the lower timeline in the list.
However, if there was no conflict in a specific property/channel... then both timelines seem to run fine together.
Is this the expected behavior?
I was sort of hoping that where two timelines were running... that the results would be additive
[Edit: I found a way to make them effectively additive by grouping the element and applying the conflicting timeline to the group instead of the element... maybe there is a better/intended way to do this...]