How many abes?
Isn't the abe that introduces aaron to time travel actually abe 2?
I think it's a joke
I guess it comes down to how you number them, and which Aaron you're referring to.
There very first time Aaron learns about TT, the Abe showing him has already gone back in time. But he didn't make a double, since he allowed his past self to enter the machine. But we're they really the same Abe? No. Abe showing Aaron TT came from a different timeline. The other Abe is going to leave for yet another timeline which we never see. So we're left with one Abe, albeit not the one from that timeline.
You could number them based on what timeline they came from. So, the original timeline would be "1", and Abe 1 travels to Timeline 2 and disrupts Aaron 2's day by showing him TT. Abe 2 enters the box and leaves Timeline 2 for some other timeline. We can call this numbering Schema 1.
Or you could number them based on the order the characters appear in a timeline. Since Timeline 2 has an "original Abe" that was just like the original Abe from Timeline 1, you could just refer to each timeline's native Abe as Abe 1, and any additional Abes increment the number. So then you'd have Abe 2 showing Aaron 1 TT, with Abe 1 entering the box. This could be numbering Schema 2.
Of course, it gets trickier when you consider the other Aaron's that Abe shows TT to. We know he does it to at least 3 Aaron's. The original Aaron, the Aaron who used the Fail Safe and made recordings, and the various Aarons who used the Fail Safe again and listen to the recordings of that 2nd Aaron.
For making recordings Aaron, using Schema 1, you could have Abe 3 showing Aaron 3 TT in timeline 4. Or Schema 2, Abe 2 showing Aaron 2 TT in timeline 4.
For the first listening to recordings Aaron, using Schema 1, you could have Abe 5 showing Aaron 5 TT in timeline 6. Or Schema 2, Abe 2 showing Aaron 3 TT in timeline 6.
Excuse me whilst I get a mop for all this brain I blew.
I think it's a joke