If you look through several thousand signatures, I'll bet you see quite a lot that look similar.
And that's not counting similar names. How many John Smiths are there, and what are the odds each has a fully 100% unique signature that can't possible look like another. Multiply that by a thousand, make the volunteers tired and overworked, and under extreme pressure with angry Trump cultists shouting at them and recording them, and no wonder they think they see doubles. And honestly there may be signature doubles in that two people with the same name sign it pretty damn similarly, especially at a hurry like when they're voting.
Why count ballots all over again during an audit? Aren't they supposed to already be counted?
What's the difference between a recount and an audit?
verifiedvoting.org
Also man of the past there is something called an inventory, which consists of counting ballots again. This is different from a re-count in the ballot processing terms, which is a specific thing. But in laymans term you re-count the votes, literally. 1 vote, 2 vote, 3 vote. So its an inventory to make sure they didn't miss a vote, and they got the number of votes right. Someone hands them a box and says this is 100 votes, but just count them again to be safe. Part of the audit is to literally hand count the ballots to make sure the machine counted the correct number. Machine says this is a stack of 100 ballots, hand count them to make sure its 100. That's the whole "Finish the audit" part. As in they're job isn't to inspect signatures, its literally to count to 100(or however many there were) while being observed to make sure they didn't steal one or put one in.
I know this wasn't recorded in Illinois but here's an example of a ballot checklist:
Part of it is literally verifying the number of ballots. That means to count them, and as they've already been counted, its a re-count.
Imagine the shit you and others would be saying if someone recorded volunteers and said "They didn't count the vote! They don't know how many votes are on this table! Its a fraud!"