Why did you say that "for money transactions, there should be one and only one chain".
While mthcl is answering, my thoughts:
1. He was under influence of Lord of the Rings, more exactly this verse:
One Ring to rule them all, One Ring to find them,
One Ring to bring them all and in the darkness bind them
In the Land of Mordor where the Shadows lie.
2. He was thinking about financial transactions that require global ordering. Pure money transfers don't require global ordering because they have A + B = B + A quality.
Nope. At that time I was probably thinking about log-correlated two-dimensional random fields.