Discernible "frequencies" of magnetic fields that do not affect each other

Sounds like more of an engineering problem than a science one. You would need magnetic shielding materials for that, Mu-Metals are typically used for such purposes and they can usually be found for free in old cathode ray tubes from television sets.

As for the science question, People often say 0 frequency in a non-redirecting magnetic field but often to side-step the more fundamental question that is actually being asked of a magnetic field having an intrinsic frequency.

And the answer to that question is, we don't know.

Or at least we think we know that a magnetic field's intrinsic frequency is 0 since there have been no publications of materials with magnetic fields that only respond to the magnetic fields of certain other materials, or a select few samples of identical materials without explanation.

Hope that answers your question thoroughly.

Consider a solenoid with its axis aligned with the alternating magnet field of a radio wave. It is likely that an iron core in the solenoid would enhance the voltage induced by the field, but any resonance effects would be associated with the capacitance of the circuit in combination with the properties of the iron. To the best of my knowledge, magnets do not have frequencies (other than their rate of oscillation, like a compass needle, if disturbed in a uniform field).

There is a way of making permanent magnets with fields that are surprisingly different from normal magnets. This can be done using "polymagnets" where pieces of different polarity are glued together. For example, this pair of magnets attract each other until they are about 1 cm apart, and then repel:

Putting a magnetic field film on one of them reveals that it has two concentric magnets:

The effect is that at longer distances the attractive dipole field dominates, but nearer the repulsive quadrupole field is stronger.

Now, for this particular application you could perhaps place magnets in a pattern so that they "shield" each other from their attraction. However, a magnetic object moving past will still be subject to the total field: there is no way of making this kind of configuration attract iron filings (say) to just magnet A and not B.

The reason is that there is just one magnetic field, and the force it exerts on paramagnetic materials is proportional to the field strength. In the electromagnetic wave case the interaction has a strong frequency dependence if the receiver is a resonant system like an antenna, but there you are dealing with a time-varying field. Yes, an oscillating magnetic field may well produce some resonance phenomena too, but then the affected particle needs to have the right shape and magnetic properties to respond right. My impression of the question is however that you want clever magnets rather than specially designed objects, right?