You're all missing the point! The key question, the BIG question here is: Where in Aazathoth's name did these kids find a dot matrix printer that was a) in working order and 2) had a driver that was compatible with today's operating systems?
As for multipart paper - the use of it goes back to impact line printer days and has little or nothing to do with the legal world (that in all probability came up with its persnickety rule years after carbon copies were a reality).
Multipart stationery is - or was - used simply to save time. There was typically one and only one printer in a computer room and it ran all night non-stop in most shops I worked in.
Many years ago a fellow consultant at a large manufacturing plant in the UK brought all development to a halt by printing nine copies of an enormous bill of materials print ( we're talking a box of fanfold greenbar per copy here). Once the protests had risen to a certain level I asked what was going on and was filled in. I then asked the lady responsible why she hadn't run it as two print runs (one on four-part, one on five) instead of nine runs on top copy only. The stunned silence from the young and restless, who had forgotten that it wasn't always simpler to just say print X copies in the ECL was quite satisfying.
I grabbed her hands as she tried to cancel her run (which would have wasted 3/4 box of paper) and called the operators and had them intervene by loading two-part in 3 of her queued runs, then sticking them into backlog until the early morning and it was Job Done.
Of course, no-one but me had ever tried to read the bottom copy of five part (mostly illegible black smudge) or the top copy (mostly letter-shaped holes punched in the paper due to the need to dial the print hammers up to Maximum Wellie just to see *anything* on the bottom copy) and so there was yet another voyage of discovery to be undertaken by the New Guard when someone remembered my advice.
Luckily that would be after my contract was up and I was long gone.
Ah, the Goodole Daze.