[CentOS] [CentOS-announce] CEBA-2015:0048 CentOS 6 nss-softokn BugFix Update

On Jan 14 10:37pm, Johnny Hughes wrote:
>
>CentOS Errata and Bugfix Advisory 2015:0048
>
>Upstream details at : https://rhn.redhat.com/errata/RHBA-2015-0048.html
>
>The following updated files have been uploaded and are currently
>syncing to the mirrors: ( sha256sum Filename )

I was surprised to find that these RPMs were modified and re-released 
with different sums yet identical version strings. Is this common 
practice?