TrackIt 20 is not affect from TI 11.
The Audit functionalty is replaced by BMC Client Management which is also not affected from TI or TI Audit.
If you want you can let the old TI run oder just shut it down, never mind.
Philipp is spot on that the scheduled audit will not have any affect with 2020 and with BMC Client Management (BCM).
However, I would recommend that you disable the scheduled auditing and when planning to move to TI 2020 with your lovely fresh clean instance, that you perhaps look at uninstalling the agent on the end points (no point having them there if they're not being used) and rolling out the new BCM agent.
Again, there shouldn't be any issue or conflict with them both running, but as one will be redundant, it doesn't need to be there.
The BCM agent is a small footprint on the client and you will be able to unlock the power of it, should you look at the additional modules you can bolt on, such as remote, patch and compliance (and all these from the single agent).
Good luck with the migration!