(This post shows pictures for Outlook 2013)
Start by selecting the contact list you want to copy contacts from. Be careful to check that you have chosen the correct account / list (eg @umb.no):
Then select the contacts you want to copy:
(use the shift key to highlight a series of entries or ctrl to mark singular entires)
Here you may highlight all using Ctrl + A and thereby copy everything. But you should, however, consider whether you actually want to keep them all. This could be a good opportunity to clean up.
Contacts with UMB and NVH addresses should either be updated or replaced with the NMBU variant.
After you have copied the contact entries, select the contact list in NMBU account where you want to add them. (If necessary, click once in the white area to make the window active):
Press Ctrl-V to paste the selected contacts::
The procedure will be practically the same in Outlook 2010, but the dialogs will look slightly different.