Part of the problem with the dual pump system is that its very hard to pick one pump that is worse than the other. One would think that one pump should handle it but I have seen enough problems with the pumps that we always replace them as a pair. There might be testing that could allow otherwise but it would cost a significant share of the price of the one possible pump one could save.
Restricting flow is not going to cause excessive current as the pump self regulate (pressure relief) at some pressure.
Most causes of high current are electrical problems in the armature or connections or a mechnically locked pump (bearings siezing).
Bosch Master, ASE Master, L1
33 years MB technician