Thermostat running 2 racks

Is it possible to use a single thermostat to run more than one rack each with separate heat tape as long as each piece of tape is the same size and length ?

Err, What type of thermostat? Some like the HerpStat-2 and up are made for that kind of thing. However, unless you can plug two temperature reading probes into the same thermostat and get it to shut off power individually I would not risk this.

The whole point of the thermostat is to either shut off or lower the amount of electricity the heating element is receiving.

If you use for example Something like a Jumpstart thermostat and a plug extension, you are likely running a variable risk. How much of a risk I do not know it could be as simple as the switch failing in such a way that it just does not give any power at all do to pulling too much.

Or it overloads breaking whatever switch type the said thermostat is using(I do believe the jumpstarts use a switch similar to a Bimetal for shutting off due to the "Click" noise they make.

Short answer...

NO, It is a possible danger to you, your animal, and your home.

What is the maximum wattage of the thermostat?
What is the wattage per foot of the heat tape?
How many feet of heat tape?

I dont go over 75% of what the thermostat can handle.

Short answer, Yes IF done correctly.

I had a herpstat 4 controlling 5 racks at one point. It worked just fine, but everything was uniform as well.