Just noticed this because I was curious. Presumably, a card part should never be blank, and we should filter that out when creating name objects.
I note this behavior that is a symptom: Card A+B exists, enter URL to A++B and you get a new card dialog. There is only on + in the displayed name, so it is stripped out there. Didn't try to save, I didn't want to risk losing the existing card.
interesting. tried this on test.dwagn.org. I saw what you saw. I tried saving but it failed (422). Not sure why exactly yet, but thanks for adding the ticket.
If I had to guess, the key ends up with an extra joint in it, so it doesn't match the other existing card. I didn't try to save, since I think if it worked it would create an invalid card. Maybe the blank name component causes it to try to create a card with a blank name, so it fails to create one of the subcards it needs. Should be a simple patch to smartname.