Why do all four versions of this verilog code have the save timing-simulation waveforms?

If you are going to ask a question you need to provide a lot of supporting info if you want more than generic responses.

What version of Quartus?

What platform (ie, Windows, Linux, etc) and version?

What simulator (Questa I believe) and version?

Can you make a test bench that instantiates all the modules at once and runs them in parallel to display exact waveforms of each?

You say they are the 'same' but we really can't validate that assertion in the data you present.