No heat mat should be run without a thermostat...
Running a heat mat without a thermostat can lead to, over heating, can cause serious burns & even death. Also there is greater risk of causing a fire...
This depends on it's wattage and size. Usually the larger ones are higher wattage.
However the simple answer is no 2 mats will be the same temp so it's best to test the one you have yourself.
Plug one in with a thermometer on it and check the temp in a while.
You will see it is indeed to hot to run for a reptile without a thermostat and even if it isn't, personally I would still want a thermostat to control it anyway.
What if your house suddenly heats up in the summer and you need ot mat to go off when it gets too warm? The mat will only be turned off if it's connected to a thermostat.
Some mats, such as the Lucky Reptile PRO, have a built-in thermal cutout preventing the mat reaching much more than 40C, that should not be considered sufficient though and the mat should still be used with a stat, just think of it as a failsafe.