Two primary filters for the main engine(which is what you have assumining one is not for fuel
polishing or a generator) can be plumbed in two different ways.
1. To use both filters together the first filter is coarse, usually 30 micron, the second is fine, usually 2 micron ( occasionally 10)
2. So you use one at a time and can switch immediately if one plugs up. In this case they are both the same, usually 10 micron.
Tracing the plumbing
should reveal which one of these set ups you have.