In theory you are correct but we don’t deal in theory the chances of having 2 inputs arrive exactly at the same time as greater the 100 billion to 1 so yes it is possible but you will never see it.
If you really want to break it down to smallest level. Since most plc communicate with the IO using a serial link even if all the inputs on a 16 point module were set to a one at the start of the data table update bit 1 would be updated before bit 2 and so on but those kinds of speed are not going to matter because we mere humans can’t respond that fast. And we are pushing the button. There are a lot of time delays in processors that we just don’t know about. Ever on a simple 60hz line it takes a full 16 ms for the zero to full value back through zero and to the full value and back to zero again( Full Cycle), and yet there is not a human on earth that can even see it let alone respond to it but a computer can do many thousand calculations in that time. Even a TV or computer monitor( Both are very slow by todays computer standards ) is only updated at a rate of 60 times per second, that’s displaying a new still picture on the screen 60 times a second but we see it as a single moving picture we are the slow ones.
Even at that all computers can still only do one thing at a time, a different thing for every clock pulse
When I was studying electronics I had professor that to try to put in perspective. A computer is a fast idiot it can count from 0 to 1 but it can do very fast and many times, we have increased the computer speed many times since then so thing just get faster but still happed one at a time.
That was before the modern day computers high speed computer we use today.
A plc will evaluate rung 2 before it dose rung 3 and rung 3 before rung 4. So the priority would be rung 2 if it is true then all the other rungs will evaluate to false so only the input on rung 2 will set the output in rung 2