I was fooling around when it found i was having difficulty with a canal in the map.
I wanted to have a series of canals in between a bunch of islands allowing you to create a barrier should you get control of the islands. Anyways, it appears that triplea will not currently accept more than 1 canal attached to a single sea zone. What'll happen is the 2nd seazone that connects to a single seazone will get an error.
Anyways I was wondering if maybe i'm mistaken and this can be done.
EDIT: Nevermind. I found an example in World At War.
Just had to change the canal attachment name