My situation was that the reverser that should have been locked out wasn’t, so when I selected reverse on both, the engine with the faulty reverser spooled up but the reverser did not deploy, so I got forward thrust on that engine and reverse thrust on the other.
Uplinker, I don't know much about the Airbus implementation, but if this happened as you described - i.e. you selected reverse but got above idle forward thrust, it violates the FAR/CS regulation 25.933:
(3) Each system must have means to prevent the engine from producing more than idle thrust when the reversing system malfunctions, except that it may produce any greater forward thrust that is shown to allow directional control to be maintained, with aerodynamic means alone, under the most critical reversing condition expected in operation.
I can't help but think there is more to what happened to you. Making sure an engine stays at idle if the T/R is not in the commanded position is one of the most basic design requirements.