You are allowed to have more than one Priority Pass membership, and you are allowed to use all of them, but only one per visit.
If Customer has multiple Program memberships, the Customer is responsible for presenting the correct Priority Pass Card or payment card to the Lounge staff for Lounge admittance, and may only use one such Program membership per entry. Any payment queries should be addressed with Priority Pass or the payment card issuer and not the individual Lounges.
https://www.prioritypass.com/en/conditions-of-use#
There is no benefit to holding more than one membership if the terms are
identical, but if (for example) you hold one membership offering unlimited visits with up to two guests, and another offering ten visits per year, the second membership could be used if you would exceed the two guest limit on a particular visit.