Phasing Two "Dissimilar" AC O Gauge Lionel Transformers On One Layout

Have Two powered loops....a common situation with some out of the box thinking transformers, one very old the other very new. Where the two loop connect is an isolation track with the differential voltage as each side is powered by a different transformer.....in phase no problem. Out of phase? How about a 40 volt spike to your fancy new computerized model train. Interested? Take a look :)