I'd suggest installing a multi-port terminal block such as the one pictured below and run your TIU output wires to the red and black posts at the bottom. You can then run your track power feeds from the ports on the terminal block to how ever many connections to the track are necessary or desired.
The terminal block should be mounted so that it's centrally located in your layout so that the power wires to the track spread out in a "star" like pattern, but it is not mandatory that all wires be of equal length.
It is ok to run both loops on one channel as long as you run enough power feeds, but it may be advantageous to split the loops between two TIU channels depending on what engines you are planning on running and whether you want to keep the loops electrically separated, again depending on what your ultimate goal is.
If you decide to run the loops on separate TIU channels, just get another terminal block and run the second channel to that block and then power wires out to the other loop.
