Teleport does not work if there are two command blocks at the same X Z coords

Given are two command blocks which are at the same X and Z coordinates. Only the Y coordinate differs.

Between the command blocks are 24 blocks space. Activating the command block using a wooden button should teleport the player from commandblock A to commandblock B and vice versa.

Command block A (lower) has code
/tp @p ~ ~+24 ~

Command block B (higher) has code
/tp @p ~ ~-24 ~

I'm able to teleport upwards using command block A, but when I activate command block B, nothing happens. I am not getting teleported 24 blocks downwards.

Workaround: Place command block B at a different X or Z coordinate.