Is there a rpm command that will check for duplicates of the same
packages.
I have problems of getting old and new version of the same rpm packages.

Jim

Yes, rpm can do this, for example;

rpm -qa --qf="%{n}-%{v}-%{r}.%{arch}\n" 'foo*' | sort

That is good as far as seeing if there is two versions of foo,
But I want rpm to let me know if there are duplicates of unknown
packages.
I'm finding during Yum updates that I'm getting conflicts between
packages that are to be updated and packages installed, and it's always
duplicate packages of the same packages, but different versions

You replace the foo part with whatever package your having a problem with;

$ rpm -qa --qf="%{n}-%{v}-%{r}.%{arch}\n" 'device*' | sort
device-mapper-1.02.09-1.0.RHEL5.i386
device-mapper-1.02.09-1.0.RHEL5.x86_64
device-mapper-multipath-0.4.7-5.x86_64


FYI: mixing to many different repos can cause problems like what your describing. Also if your running a mixed mode environment (32 and 64 bit apps and libs) then yum at times can be a problem.

It might help if you could show an actual problem instead of describing what you see.