Changing versions (1.7.10 to 14w32a to 1.7.10) Messed my signs up

Explanation:
I had placed several signs with different text on all of them and had many item frames in my City. I wanted to see the new snapshots and got on 14w32a (Nice work by the way! Looks awesome!) I got on the same world all was fine, but when i went back to 1.7.10 All the signs were weird and item frames fell off without the items inside! The signs looked like this:
"What I had put on the signs here"
"Blah Blah Blah"
"Somethin whatever"
null
When there was nothing it said null...
How to recreate:
1. Place Signs and item frames in world, in 1.7.10
2. Go to 14w32a on same world
3. Go back to 1.7.10 and you should see for your self
---ALSO---
One of the signs said GARAGE SALE
<<<<
<<<<
GARAGE SALE
and ended up with:
"GARAGE SALE"
"/u003c/u003c/u
"/u003c/u003c/u
"GARAGE SALE"
So, As far as I understand, its repeating the code but not what was inside or what it meant... Thanks!