What happens if Bob creates a stream towards Alice when there is already a stream from Alice to Bob?

[PaulRBerg]

Imagine you have a stream $s_1$ from $A$ to $B$, and then $B$ decides to create a new stream $s2$ back to $A$. What should the protocol do in this case? There are two options:

1. Create $s2$ and keep it running alongside $s1$.
2. Delete $s1$ and if $s2$’s flow rate:
   1. Matches that of $s1$, do nothing.
   2. Is smaller than that of $s1$, keep $A$ the tail and $B$ the head.
   3. Is greater than that of $s1$, make $B$ the tail and $A$ the head.

We will go with option 2 because we don't want to enable multiple edges between users.