Sync Tunze waveboxes

In order to sync 2 waveboxes, do I need either 2 Tunze cable 1's or 2 Tunze cable 2's?
Right now I have 1 "Tunze cable 1" and 1 "Tunze cable 2".

Thanks,
Mitch

if you have 2 identical cables both pumps will run synchronously

but you can achieve this also with a pair of differnent cables: set the function of both interfaces (e.g. L1 and L2) to the same (e.g. pump 1)