Thought this should go into complaints first in case it is not a bug.
The first time this happened thought it was just me... yet just now it was obvious that the software was allowing it.
While firing on a Maul with bow a magic user jumped in and the message was something like "<character name> group shares the attack" or something like that. The time this happened before the other character was using magic too.
If this is intentional then it is very frustrating. If it is not intentional then let me know so that a bug report can be made.