First tab. I've written this all tonight, and I've been wonky all day, but Hell, I like this so far and any and all feedback and criticism would be greatly appreciated.
Reminds me a lot of one of my own articles, SCP-1153, in that they're both immortal, non-sentient human test subjects with markings on their bodies that are designed to recover from any illness or injury.
However, you've clearly taken it in a different direction. The addendum is really quite good, and although I found it slightly narmy in a few places (the "We tried to create the perfect human being" line in the last document seems rather cliche) it's not really all that bad in this respect.
One thing though- you mention repeatedly the process that turns people into these things (apparently simple and bad-guarded enough that an untrained girl was able to clone herself during bring-your-daughter-to-work day). There should be some mention of that process in the article somewhere, even if it's just the Foundation admitting that they don't understand the process, or the relevant equipment/documentation to perform the process was not found at the laboratory.
Sorry I couldn't be more in-depth, azzle, but all in all I think this is pretty good and I would upvote.
I like what you've got here, though you've given me the opportunity to make a criticism that doesn't come along very often.
I feel like Addendum-XXXX-Alpha gives too much away about the SCP. It makes it just a little too blatant. You've written it well enough that by the time I reached Table-XXXX-Psi I had a pretty good theory in my head about what they were, but then I got to the addendum and you pretty much said "yep, it's what you thought, plus this, this, and also that."
You've done a good job, but I think that you should trim it just a bit, you stripped away a little too much of the intrigue.
EDIT: Actually, while I do appreciate the criticism, I've read over the draft a few times, and, after a little tweaking on certain areas, personally felt that there was no real need to cut out too much. Thank you though!