To fix an error like that I just hit f3+a and it will reload.
I can confirm! Still a bug in 14w29b.
I noticed the bug disappear when I restarted minecraft after creating several new worlds (to make sure this was an actual bug). Before the restart, floating item frames with workbenches in them would appear at those coords. No mods were in use other than the snapshot.
REPLY Kumasasa: The link you gave me showed how the item frames are duped from another world. I did not have any other worlds in my saves with item frames......
This is an intentional feature. The 'L' stands for 'levels'. Adding the 'L' at the end of the amount of XP just gives you that many levels. Without the 'L' it would be in single XP orbs.
http://minecraft.gamepedia.com/Commands