When creating a line of command blocks that pass a redstone block forward every tick, it activates touching repeat blocks twice.
Here's the arrangement for the first screenshot:

• Normal command block: clone ~ ~ ~-1 ~ ~ ~-1 ~1 ~ ~-1 replace move
• Repeating command block: say 1

Here's the arrangement for the second and third screenshot:

• Repeating command block: say 1
• Chain command block: clone ~ ~ ~2 ~ ~ ~2 ~1 ~ ~2 replace move

The bug occurs in both cases. If required, I can shoot video footage.