[CentOS-devel] i386/noarch RPMS differences between x86_64 and i386 repos?

I have my own local copies of the CentOS 5.3 x86_64 and i386 repos - and 
to save space, I ran 'hardlink' over the RPMS directories - however it 
found that a number of the i386 and noarch RPMS in the x86_64 tree were 
'different' from the matching RPMS in the i386 tree.

Out of the 1186 i386/noarch RPMS on the 5.3 x86_64 iso image, 222 are 
different from the matching i386/noarch RPMS from the i386 iso image

The difference appears to be the 'Signature' date - the rest of the info 
from 'rpm -qi' appears identical.

Most of these 'different' RPMS are ones that have been updated in 5.3

Is there a reason why these RPMS have a different signature date?

Not a major issue ...

Thanks

James Pearson