The "Fortune" abiliy seems to work on all metal deco blocks, so instead of one you can get up to 3 ingots from one deco block when breaking it. Since you only need one ingot in the anvil to craft a deco block, I would call that a dupe glitch.

Testing:

Result:

Version: 1.0.27_X4193
Only NEI and NTM installed.

btw: the Deco Light Emitter could use an upper beamwidth limit

The issue with deco blocks is known and should already be fixed (although the fix is probably not in the latest release yet).

A size limit for beam emitters doesn't exist since if you, for whatever reason, need a beam this large then you should be able to make a beam this large. A base on a server I was on for example was supposed to have a similarly sized beam at the core.

Sry, I searched if this issue was already reported but didn't find it.

Ah okay.

Should be fixed in X4200.