or is that just punishing yourself??

Depends on what your goal is. For weight loss and general fitness? No. If it's a mental accountability self-punishment thing? Maybe.

would any normal person punish themselves and do double workouts though do you think?

I've been known to do a double work out if I miss one or if I know the next day I am going to be too buisy to work out. I only strength train though so normally I do upper body one day and lower body the next so as long as I get a bake in between the two its not exactly punishment.

It comes down to the type of work out you mean. If you do a CKD diet or carb backloading, then making sure you have total glycogen depletion is important.
If you do splits in the gym then doing to days worth in one is possible but if you include compound lifts in this they will not be as effective as normal.
If you do cardio based exercise then basically you should be pretty burnt out at the end of your session anyway, and doing a second right away should not be possible.

Personally if I miss one days worth of exercise I just right it off, and make a mental note not to do that again !! :-D

No. If you're new to exercise you'd only be setting yourself up for injury.