Need help with probe placement

Hi, I have this rack from Reptile Basics:

http://www.reptilebasics.com/reptile...ics-ve-2-rack/

My question is - this rack has two levels and each level has a recessed groove to put the probe into. I am using a VE-300 for my main thermostat and a VE-100 for a backup/safety thermostat.

I have the probe for the VE-300 in the groove on the top shelf and the VE-100 probe is on the lower shelf in the groove.

Usually when I use two thermostats on the same setup I place the probes right next to each other but on this rack - you only have a groove for one probe on each level.

Is this the correct way to set it up when using two thermostats? And, does it matter which probe is on which level?

Please advise.