It’s in the title 
they have 6 volume and 6 weight for me, cant confirm it.
[URL=http://s1050.photobucket.com/user/Ferodaktyl/media/cdda/2x4bug.png.html]
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Since your encumberance is, like, a million and ten, the game assumes you’re suffering greatly and grants you the power to suffer even more, only it doesn’t show. It’s your wisdom tooth of the game - slow, painful, and it pinpoints that fact when you open the classic inventory screen.
If you try and remove any of the worn items above, you’re dead. You’re now the Wisdom Tooth Crawler.
Question, did you try playing defense mode? I seem to remember that there was some special code for defense mode that sets the weight/volume of 2x4’s to 0, it’s possible that it is just carrying over into normal mode.
yes, it happened after playing defense