In QTP 8.2 we have  Quick Test Plus where we have a utility 
called REPOSITORIES MERGE UTILITY from where you can add 
the rep's and save it in a destination Rep

Start > programs > Quick Test Plus > utilities > 
Repositories Merges Utility

Uday Kumar T.V.

In QTP9.0 There is Object Repository Manager Tool is there
under Resource Menu.In This Object Repository Merge Tool i s
there.Using this tool we can merge ORs.

In QTP 9.0, We can two or more OR's

1. We can update Shared Object Repository by merging local
object repository. But Check points and output values are
not merged. We need to export them and all them to OR after
the merging is done.

2.We can merge one or more shared object repositoroes into
one OR.

yes we can merge the object repositories

-->go to Resources
-->select object respository manager
-->go to tools
-->select object repository merge tool
-->new window will appear with name "new merge"
-->give the path of the primary and secondary file
-->click ok

a window will appear with conflicts

if u want to change that conflicts go to "resolution options" and do the modifications