Can someone please tell me why this is occurring?
Probably not beyond observing that most likely you accidentally did a lot more than you think you did.
It's like Ubuntu mutated with Raspbian.
Yeah, that's...well it did not happen through airborne infection if you get my drift. And the pi itself doesn't have the potential to do this by using first one card then the other.
So again, something most likely went wrong when you were doing this stuff with swapping the
config.txts around. You didn't go into detail about how you did that but I assume it was on some other computer.
I absolutely cannot lose all of my Python scripts.
Okay, so if there is one lesson you learn from all of this, please let it be that if you have things you absolutely cannot lose, you absolutely need to keep them backed up properly. I know that programming is much more fun and interesting than learning to use tools like
rsync but once you sort this mess out, before you go back to programming anything, you MUST sit down, look at options of that sort, and start learning how to use them. No system is bullet proof. If you dump a coffee on a pi and SD card you just lost $40-50 bucks, that's irritating. If that pi had two hundred or a thousand hours worth of work on it and that's now gone it is going to be way beyond "irritating". That's why things like
Anyway, what you need to do is focus on the priority of retrieving your irreplaceable data. To do that, you have to have a look at the root partition on the SD card. To do that properly you need one of three things that are within reach but, again, may require some doing some not-as-fun-as-coding stuff:
A computer with an SD card slot (or USB + SD Card adapter) running some form of linux.
Same computer running any OS that can run virtual machine software (the two most popular are probably VirtualBox and VMware) with some form of linux inside. This is probably the most complicated option, but it does save you the need to, e.g, set up a dual boot system with whatever OS you usually use.
A linux "live CD", presuming your computer has a DVD drive it can boot from (and really these are "live DVDs" now, the images don't fit on CDs). These are slow and there are a limited number of them, beware that some distros have gotten into the strange habit of calling their installer images "live CDs" when all they are really capable of is installing a system onto a hard drive. However, this Debian page strongly implies it can be used as a complete system run from the DVD (be warned this is very slow, but you don't have to use it for much). Since Raspbian is based on Debian, it should also be very familiar.
There are some other options here, e.g., I believe it is not so hard to access an ext4 partition from OSX and not impossible from MS Windows, but one way or another you need access, on something other than the pi, to the root filesystem on the SD card. Doing this means you don't have to login, etc., etc., you can just access everything the way you would stuff that's on an SD card or thumb drive.
That's the first step in attending to your first priority, doing your best to rescue your python work. Do not try to do it by screwing around with the card more so you can put it back in the pi again and get it that way -- doing anything to the card at this point is just going to increase the chances that you lose everything.