The S7-1200 CPU operates ten RTMs (Run-Time hour Meters). The NR input parameter to the RTM instruction determines which of those ten that instruction uses. Since the value of NR is the same, i.e. 0, on all of the RTM instructions in the program, the CPU uses the same, i.e. only one, run-time hour meter for all of those instructions.
So when you wrote "I have more than one RTM in my program," you should have written "I have only one RTM in my program" instead.
The PLC cares not a whit what we want it to do, but it will mercilessly and inexorably do exactly what we tell it to do.
The only thing worse than the PLC not doing what we want it to do is when it does exactly what we tell it to do.