Check In/Check out

Hi All,

I am currently using check in / out over my records. I am facing some problem in understanding the functionality. The scenario is as follows.

I have two users u1 and u2 with roles as Admin and catalog user.

If u1 checks out records(exclusively) u2 cant make any changes to the records but if we click the all versions option then we get the duplicate copy which is lock and the options Check In and Roll back becomes available but still we cant make any changes to it, But we can use these options, i.e., we can either roll back or do a check in over the locked records......how can this happen if the records are checked out by some user how can another user commit or check in or roll back over these records. After dooing this the check out for these records over the parent user also vanishes.....

Can any one please go through it...

Thanxs