PostRevision will not have exact post of the specific version. It will have the post with modifications like below
<del>Hi, </del>This is example post <ins>revision</ins>.
Hi, This is example post revision.
And it will start from number 2 only. Because revision 2 is the modifications of the post version 1 from version 2.
If you need the exact post instead then you may have to find an another way. Explore the code 
.