Two Pistons above each other behave unexpectedly when facing North/South

When placing two pistons above each other and powering a block next to the top Piston with a repeater while having redstone below that block, the outcome is different for each location. This only works if the repeater feeds into the block while facing north or south, otherwise only the upper piston will extend.
Whether the upper or the lower piston is extended only depends on the location of the pistons. Building the same setup on a different map with a different seed at the same coordinates will result in the same pattern (For example, if the lower piston is at (-664, 56, 100) and the repeater faces north, the lower piston will extend. When building it at (-666, 56, 100) the upper piston will extend).
This happens in both singleplayer and multiplayer/Creative and Survival.