Double plats will always work in waste fire ignition systems.
Stock, the factories often use a double plat on one leg, and a single plat on the other leg.
Because of the +to- and - to + firing, erosion is on the center or side electrode.
Cheapness lets them put in a single plat plug . If you replace with singles, you have to put them in the right hole.
Most replacement plugs will simply just use the double plat, anyway.