When changing the "Marker" tag on an armor stand from 0 to 1, it can produce footstep sounds

Cannot confirm for 1.8.2-pre4, does this happen always or only sometimes?

Only sometimes. Just make a clock continuously setting the tag to 1 and 0 and you will hear them.

Is this still an issue in current release 1.8.7 ?

Not every time. But yes I can confirm this.

From my tests the sound happens when I take a couple of steps then run the command.
To recreate:
Set down an ArmorStand and take two steps back away from the ArmorStand run the command and you should hear the sound. Take two steps forward and repeat, same outcome. It seems to happen only on certain step sounds, I'm not too sure though.
But just running the command over and over does nothing. This bug seems to require the player(perhaps even a mob I have not tested) to take steps near the ArmorStand.
A similar bug happens when you use /playsound and then do something to cause block updates you sometimes hear a residual sound.

I was within 6 blocks of the ArmorStand. Could you add some screenshots of how you set it up maybe if i recreate it as close to yours as i can I can reproduce your issue. Like the type of clock you used, and were you using a default ArmorStand?

I simply had 2 command blocks, one with the command

entitydata @e[type=ArmorStand] {Marker:0}

and one with

entitydata @e[type=ArmorStand] {Marker:1}

each being triggered in sequence. The armor stand has all the default tags (except Marker, obviously).

If you can't replicate this, it could just be probability. Use a faster clock and more armor stands, maybe that will help.

See the screenshot on how to do it.

entitydata @e[type=ArmorStand] {Marker:1}

entitydata @e[type=ArmorStand] {Marker:0}

Reopened.

Can't reproduce for 1.10.2