hmmmm. I don't think that is a "real" active/active array. You have two contollers but I think each owns it's own LUN's... So when you created the LUN's you did it on each controller in separate right?
the 2040 worked that way and only high end array are tru active active like a vmax. So... I think you have ALUA but it's not avaliable for iscsi as far as I remember. Without it, the only way SP1 would pick up the LUNs on SP2 would be on a failover. If thats the case, make sure you divided the storage on the two controllers