Yes, of course there's some fraud
It would be astonishing if most of the petitions didn't have at least some fraud. Since this is by far the biggest petition it presumably attracts more.
It quite possibly includes lots of idiots thinking they can boost the petition by putting in false addresses, and lots more idiots thinking they can sabotage the petition by putting in false addresses and then claiming that because some are fraudulent then the whole thing is invalid.
Anyone who wants to actually affect it would have to do a lot of fraudulent entries - it's well over three and a half million now.