Investigating a Forged PDF

The phrase "indentured" means "cut into sharp pointy teeth" (a zig zag pattern). The contract is written out in triplicate by hand on a large sheet. Being hand-cut after the whole document is signed, it is hard to perfectly replicate that cut. Additionally, someone would write "A BIG LATIN WORD" over the area to be cut, so to forge the other piece(s) you have to recreate the demi-penstrokes plausibly.

When two copies don't match, someone is lying. The essential third copy is stored at the Notary Office, which tells you whom is lying.

"Indentured servants" were bound by such a contract.

But for official documents used as legal proof, staying as close as possible to the original is required for a forgery to avoid sticking out simply for having the wrong formatting. But you usually won't find those posted publicly on the internet.

this is a lazy, clumsy editing attempt, done through a document registration service which exists to prevent exactly this and yet, you have to be an experienced nerd (eg https://en.wikipedia.org/wiki/Matthew_Garrett has a doctorate and decades of software development experience) who will jump through a bunch of hoops to even begin to build a case beyond he-said-she-said. And he still doesn't have a settlement or criminal conviction in hand, so he's not even half done... Or look at the extensive forensics in the Craig Wright case just to establish simple things like that they were edited or backdated to a legally acceptable level.

Meanwhile, the original PDF edit in question took maybe 5 minutes with entry-level PDF tools.

Xournal++

Have multiple copies of everything, at the time of signing. I usually get two copies of a contract. I sign them both, the other party signs them both, and we each get a copy. Same with any amendments or codicils.

We are each responsible for maintaining our own copy.

There should be a way to do this digitally.

There is a lot of movement in that space right now because European governments use this data for VAT processing and have discovered that signed machine-readable data is a lot better than stacks of paper audited by humans

Another part of the solution is reporting such cases and making sure these people are charged with fraud

If you just mean that they had the second version in their system but never intended to send it at all, then I'm not sure what possible innocent explanation there would be for uploading a newly modified version of an already signed lease that's run its course.