ch-10: mention route correlation within route itself

10_onion_routing.asciidoc

@@ -672,7 +672,7 @@ Now Bob can keep the first half 1300 bytes, and discard the extended (filler) 13
 
 Bob now has a 1300 byte onion packet to send to the next hop. It is almost identical to the onion payload that Alice had created for Chan, except that the last 65 or so bytes of filler was put there by Bob and will be different.
 
-No one can tell the difference between filler put there by Alice and filler put there by Bob. Filler is filler! It's all random bytes anyway.
+No one can tell the difference between filler put there by Alice and filler put there by Bob. Filler is filler! It's all random bytes anyway. Note that if Bob (or one of Bob's other aliases) is present in the route in two disctinct locations, then they can tell the difference as the base protocol always uses the same payment hash across the entire route. Atomic Multipath Payments (AMP), and Point Time Locked Contrats (PTLCs) eliminate the correlation vector by randomizing the payment idenitifer across each route/hop.
 
 ==== Bob constructs the new onion packet